❤️ Communication 🐲

"Communication (from Latin communicare, meaning "to share") is the act of conveying meanings from one entity or group to another through the use of mutually understood signs, symbols, and semiotic rules. The main steps inherent to all communication are: # The formation of communicative motivation or reason. # Message composition (further internal or technical elaboration on what exactly to express). # Message encoding (for example, into digital data, written text, speech, pictures, gestures and so on). # Transmission of the encoded message as a sequence of signals using a specific channel or medium. # Noise sources such as natural forces and in some cases human activity (both intentional and accidental) begin influencing the quality of signals propagating from the sender to one or more receivers. # Reception of signals and reassembling of the encoded message from a sequence of received signals. # Decoding of the reassembled encoded message. # Interpretation and making sense of the presumed original message. The scientific study of communication can be divided into: * Information theory which studies the quantification, storage, and communication of information in general; * Communication studies which concerns human communication; * Biosemiotics which examines communication in and between living organisms in general. * Biocommunication which exemplifies sign-mediated interactions in and between organisms of all domains of life, including viruses. The channel of communication can be visual, auditory, tactile/haptic (e.g. Braille or other physical means), olfactory, electromagnetic, or biochemical. Human communication is unique for its extensive use of abstract language. Development of civilization has been closely linked with progress in telecommunication. Non-verbal communication Nonverbal communication describes the processes of conveying a type of information in a form of non-linguistic representations. Examples of nonverbal communication include haptic communication, chronemic communication, gestures, body language, facial expressions, eye contact etc. Nonverbal communication also relates to the intent of a message. Examples of intent are voluntary, intentional movements like shaking a hand or winking, as well as involuntary, such as sweating. Speech also contains nonverbal elements known as paralanguage, e.g. rhythm, intonation, tempo, and stress. It affects communication most at the subconscious level and establishes trust. Likewise, written texts include nonverbal elements such as handwriting style, the spatial arrangement of words and the use of emoticons to convey emotion. Nonverbal communication demonstrates one of Paul Watzlawick's laws: you cannot not communicate. Once proximity has formed awareness, living creatures begin interpreting any signals received.Wazlawick, Paul (1970's) opus Some of the functions of nonverbal communication in humans are to complement and illustrate, to reinforce and emphasize, to replace and substitute, to control and regulate, and to contradict the denotative message. Nonverbal cues are heavily relied on to express communication and to interpret others' communication and can replace or substitute verbal messages. However, non- verbal communication is ambiguous. When verbal messages contradict non-verbal messages, observation of non-verbal behaviour is relied on to judge another's attitudes and feelings, rather than assuming the truth of the verbal message alone. There are several reasons as to why non-verbal communication plays a vital role in communication: "Non-verbal communication is omnipresent." (Burgoon, J., Guerrero, L., Floyd, K., (2010). Nonverbal Communication, Taylor & Francis. p. 3 ) They are included in every single communication act. To have total communication, all non-verbal channels such as the body, face, voice, appearance, touch, distance, timing, and other environmental forces must be engaged during face-to-face interaction. Written communication can also have non-verbal attributes. E-mails, web chats, and the social media have options to change text font colours, stationary, add emoticons, capitalization, and pictures in order to capture non-verbal cues into a verbal medium. "Non-verbal behaviours are multifunctional." (Burgoon et al., p. 4) Many different non- verbal channels are engaged at the same time in communication acts and allow the chance for simultaneous messages to be sent and received. "Non-verbal behaviours may form a universal language system." Smiling, crying, pointing, caressing, and glaring are non-verbal behaviours that are used and understood by people regardless of nationality. Such non-verbal signals allow the most basic form of communication when verbal communication is not effective due to language barriers. Verbal communication Verbal communication is the spoken or written conveyance of a message. Human language can be defined as a system of symbols (sometimes known as lexemes) and the grammars (rules) by which the symbols are manipulated. The word "language" also refers to common properties of languages. Language learning normally occurs most intensively during human childhood. Most of the large number of human languages use patterns of sound or gesture for symbols which enable communication with others around them. Languages tend to share certain properties, although there are exceptions. There is no defined line between a language and a dialect. Constructed languages such as Esperanto, programming languages, and various mathematical formalisms are not necessarily restricted to the properties shared by human languages. As previously mentioned, language can be characterized as symbolic. Charles Ogden and I.A Richards developed The Triangle of Meaning model to explain the symbol (the relationship between a word), the referent (the thing it describes), and the meaning (the thought associated with the word and the thing). The properties of language are governed by rules. Language follows phonological rules (sounds that appear in a language), syntactic rules (arrangement of words and punctuation in a sentence), semantic rules (the agreed upon meaning of words), and pragmatic rules (meaning derived upon context). The meanings that are attached to words can be literal, or otherwise known as denotative; relating to the topic being discussed, or, the meanings take context and relationships into account, otherwise known as connotative; relating to the feelings, history, and power dynamics of the communicators. Contrary to popular belief, signed languages of the world (e.g., American Sign Language) are considered to be verbal communication because their sign vocabulary, grammar, and other linguistic structures abide by all the necessary classifications as spoken languages. There are however, nonverbal elements to signed languages, such as the speed, intensity, and size of signs that are made. A signer might sign "yes" in response to a question, or they might sign a sarcastic-large slow yes to convey a different nonverbal meaning. The sign yes is the verbal message while the other movements add nonverbal meaning to the message. Written communication and its historical development Over time the forms of and ideas about communication have evolved through the continuing progression of technology. Advances include communications psychology and media psychology, an emerging field of study. The progression of written communication can be divided into three "information communication revolutions": # Written communication first emerged through the use of pictographs. The pictograms were made in stone, hence written communication was not yet mobile. Pictograms began to develop standardized and simplified forms. # The next step occurred when writing began to appear on paper, papyrus, clay, wax, and other media with commonly shared writing systems, leading to adaptable alphabets. Communication became mobile. # The final stage is characterized by the transfer of information through controlled waves of electromagnetic radiation (i.e., radio, microwave, infrared) and other electronic signals. Communication is thus a process by which meaning is assigned and conveyed in an attempt to create shared understanding. Gregory Bateson called it "the replication of tautologies in the universe.Bateson, Gregory (1960) Steps to an Ecology of Mind This process, which requires a vast repertoire of skills in interpersonal processing, listening, observing, speaking, questioning, analyzing, gestures, and evaluating enables collaboration and cooperation. Business/Corporate Business communication is used for a wide variety of activities including, but not limited to: strategic communications planning, media relations, internal communications, public relations (which can include social media, broadcast and written communications, and more), brand management, reputation management, speech-writing, customer-client relations, and internal/employee communications. Companies with limited resources may choose to engage in only a few of these activities, while larger organizations may employ a full spectrum of communications. Since it is relatively difficult to develop such a broad range of skills, communications professionals often specialize in one or two of these areas but usually have at least a working knowledge of most of them. By far, the most important qualifications communications professionals must possess are excellent writing ability, good 'people' skills, and the capacity to think critically and strategically. Business communication could also refer to the style of communication within a given corporate entity, i.e. email conversation styles, or internal communication styles. Political Communication is one of the most relevant tools in political strategies, including persuasion and propaganda. In mass media research and online media research, the effort of the strategist is that of getting a precise decoding, avoiding "message reactance", that is, message refusal. The reaction to a message is referred also in terms of approach to a message, as follows: * In "radical reading" the audience rejects the meanings, values, and viewpoints built into the text by its makers. Effect: message refusal. * In "dominant reading", the audience accepts the meanings, values, and viewpoints built into the text by its makers. Effect: message acceptance. * In "subordinate reading" the audience accepts, by and large, the meanings, values, and worldview built into the text by its makers. Effect: obey to the message.Danesi, Marcel (2009), Dictionary of Media and Communications. M.E.Sharpe, Armonk, New York. Holistic approaches are used by communication campaign leaders and communication strategists in order to examine all the options, "actors" and channels that can generate change in the semiotic landscape, that is, change in perceptions, change in credibility, change in the "memetic background", change in the image of movements, of candidates, players and managers as perceived by key influencers that can have a role in generating the desired "end-state". The modern political communication field is highly influenced by the framework and practices of "information operations" doctrines that derive their nature from strategic and military studies. According to this view, what is really relevant is the concept of acting on the Information Environment. The information environment is the aggregate of individuals, organizations, and systems that collect, process, disseminate, or act on information. This environment consists of three interrelated dimensions, which continuously interact with individuals, organizations, and systems. These dimensions are known as physical, informational, and cognitive. Family Family communication is the study of the communication perspective in a broadly defined family, with intimacy and trusting relationship.Turner, L.H., & West, R.L. (2013). Perspectives on family communication. Boston: McGraw-Hill. The main goal of family communication is to understand the interactions of family and the pattern of behaviors of family members in different circumstances. Open and honest communication creates an atmosphere that allows family members to express their differences as well as love and admiration for one another. It also helps to understand the feelings of one another. Family communication study looks at topics such as family rules, family roles or family dialectics and how those factors could affect the communication between family members. Researchers develop theories to understand communication behaviors. Family communication study also digs deep into certain time periods of family life such as marriage, parenthood or divorce and how communication stands in those situations. It is important for family members to understand communication as a trusted way which leads to a well constructed family. Interpersonal In simple terms, interpersonal communication is the communication between one person and another (or others). It is often referred to as face-to-face communication between two (or more) people. Both verbal and nonverbal communication, or body language, play a part in how one person understands another. In verbal interpersonal communication there are two types of messages being sent: a content message and a relational message. Content messages are messages about the topic at hand and relational messages are messages about the relationship itself. This means that relational messages come across in how one says something and it demonstrates a person's feelings, whether positive or negative, towards the individual they are talking to, indicating not only how they feel about the topic at hand, but also how they feel about their relationship with the other individual. There are many different aspects of interpersonal communication including: * Audiovisual Perception of Communication Problems.Barkhuysen, P., Krahmer, E., Swerts, M., (2004) Audiovisual Perception of Communication Problems, ISCA Archive http://www.isca-speech.org/archive The concept follows the idea that our words change what form they take based on the stress level or urgency of the situation. It also explores the concept that stuttering during speech shows the audience that there is a problem or that the situation is more stressful. * The Attachment Theory.Bretherton, I., (1992) The Origins of Attachment Theory: John Bowlby and Mary Ainsworth, Developmental Psychology, 28, 759-775 This is the combined work of John Bowlby and Mary Ainsworth (Ainsworth & Bowlby, 1991) This theory follows the relationships that builds between a mother and child, and the impact it has on their relationships with others. * Emotional Intelligence and Triggers.Mazza, J., Emotional Triggers, MABC, CPC Emotional Intelligence focuses on the ability to monitor ones own emotions as well as those of others. Emotional Triggers focus on events or people that tend to set off intense, emotional reactions within individuals. * Attribution Theory.Bertram, M., (2004) How the Mind Explains Behavior: Folk Explanations, Meaning, and Social Interaction, MIT Press, This is the study of how individuals explain what causes different events and behaviors. * The Power of Words (Verbal communications). Verbal communication focuses heavily on the power of words, and how those words are said. It takes into consideration tone, volume, and choice of words. * Nonverbal Communication. It focuses heavily on the setting that the words are conveyed in, as well as the physical tone of the words. * Ethics in Personal Relations.Lipthrott, D., What IS Relationship? What is Ethical Partnership? It is about a space of mutual responsibility between two individuals, it's about giving and receiving in a relationship. This theory is explored by Dawn J. Lipthrott in the article What IS Relationship? What is Ethical Partnership? * Deception in Communication.Hearn, J., (2006) Interpersonal Deception Theory: Ten Lessons for Negotiators This concept goes into that everyone lies, and how this can impact relationships. This theory is explored by James Hearn in his article Interpersonal Deception Theory: Ten Lessons for Negotiators * Conflict in Couples.Lenhart, A., Duggan, M., (2014) Couples, the Internet, and Social Media This focuses on the impact that social media has on relationships, as well as how to communicate through conflict. This theory is explored by Amanda Lenhart and Maeve Duggan in their paper Couples, the Internet, and Social Media Barriers to effectiveness Barriers to effective communication can retard or distort the message or intention of the message being conveyed. This may result in failure of the communication process or cause an effect that is undesirable. These include filtering, selective perception, information overload, emotions, language, silence, communication apprehension, gender differences and political correctness.Robbins, S., Judge, T., Millett, B., & Boyle, M. (2011). Organisational Behaviour. 6th ed. Pearson, French's Forest, NSW pp. 315–317. This also includes a lack of expressing "knowledge- appropriate" communication, which occurs when a person uses ambiguous or complex legal words, medical jargon, or descriptions of a situation or environment that is not understood by the recipient. * Physical barriers – Physical barriers are often due to the nature of the environment. An example of this is the natural barrier which exists when workers are located in different buildings or on different sites. Likewise, poor or outdated equipment, particularly the failure of management to introduce new technology, may also cause problems. Staff shortages are another factor which frequently causes communication difficulties for an organization. * System design – System design faults refer to problems with the structures or systems in place in an organization. Examples might include an organizational structure which is unclear and therefore makes it confusing to know whom to communicate with. Other examples could be inefficient or inappropriate information systems, a lack of supervision or training, and a lack of clarity in roles and responsibilities which can lead to staff being uncertain about what is expected of them. * Attitudinal barriers– Attitudinal barriers come about as a result of problems with staff in an organization. These may be brought about, for example, by such factors as poor management, lack of consultation with employees, personality conflicts which can result in people delaying or refusing to communicate, the personal attitudes of individual employees which may be due to lack of motivation or dissatisfaction at work, brought about by insufficient training to enable them to carry out particular tasks, or simply resistance to change due to entrenched attitudes and ideas. * Ambiguity of words/phrases – Words sounding the same but having different meaning can convey a different meaning altogether. Hence the communicator must ensure that the receiver receives the same meaning. It is better if such words are avoided by using alternatives whenever possible. * Individual linguistic ability – The use of jargon, difficult or inappropriate words in communication can prevent the recipients from understanding the message. Poorly explained or misunderstood messages can also result in confusion. However, research in communication has shown that confusion can lend legitimacy to research when persuasion fails.What Should Be Included in a Project Plan. Retrieved December 18, 2009 * Physiological barriers – These may result from individuals' personal discomfort, caused—for example—by ill health, poor eyesight or hearing difficulties. * Bypassing – This happens when the communicators (the sender and the receiver) do not attach the same symbolic meanings to their words. It is when the sender is expressing a thought or a word but the receiver gives it a different meaning. For example- ASAP, Rest room * Technological multi-tasking and absorbency – With a rapid increase in technologically-driven communication in the past several decades, individuals are increasingly faced with condensed communication in the form of e-mail, text, and social updates. This has, in turn, led to a notable change in the way younger generations communicate and perceive their own self-efficacy to communicate and connect with others. With the ever-constant presence of another "world" in one's pocket, individuals are multi-tasking both physically and cognitively as constant reminders of something else happening somewhere else bombard them. Though perhaps too new an advancement to yet see long-term effects, this is a notion currently explored by such figures as Sherry Turkle. * Fear of being criticized – This is a major factor that prevents good communication. If we exercise simple practices to improve our communication skill, we can become effective communicators. For example, read an article from the newspaper or collect some news from the television and present it in front of the mirror. This will not only boost your confidence but also improve your language and vocabulary. * Gender barriers – Most communicators whether aware or not, often have a set agenda. This is very notable among the different genders. For example, many women are found to be more critical when addressing conflict. It's also been noted that men are more likely than women to withdraw from conflict. =Cultural aspects= Cultural differences exist within countries (tribal/regional differences, dialects and so on), between religious groups and in organisations or at an organisational level – where companies, teams and units may have different expectations, norms and idiolects. Families and family groups may also experience the effect of cultural barriers to communication within and between different family members or groups. For example: words, colours and symbols have different meanings in different cultures. In most parts of the world, nodding your head means agreement, shaking your head means "no", but this is not true everywhere.Nageshwar Rao, Rajendra P. Das, Communication skills, Himalaya Publishing House, 9789350516669, p. 48 Communication to a great extent is influenced by culture and cultural variables. Understanding cultural aspects of communication refers to having knowledge of different cultures in order to communicate effectively with cross culture people. Cultural aspects of communication are of great relevance in today's world which is now a global village, thanks to globalisation. Cultural aspects of communication are the cultural differences which influence communication across borders. # Verbal communication refers to a form of communication which uses spoken and written words for expressing and transferring views and ideas. Language is the most important tool of verbal communication. Countries have different languages. A knowledge of languages of different countries can improve cross-cultural understanding. # Non-verbal communication is a very wide concept and it includes all the other forms of communication which do not use written or spoken words. Non verbal communication takes the following forms: #* Paralinguistics are the elements other than language where the voice is involved in communication and includes tones, pitch, vocal cues etc. It also includes sounds from throat and all these are greatly influenced by cultural differences across borders. #* Proxemics deals with the concept of the space element in communication. Proxemics explains four zones of spaces, namely intimate, personal, social and public. This concept differs from culture to culture as the permissible space varies in different countries. #* Artifactics studies the non verbal signals or communication which emerges from personal accessories such as the dress or fashion accessories worn and it varies with culture as people of different countries follow different dress codes. #* Chronemics deals with the time aspects of communication and also includes the importance given to time. Some issues explaining this concept are pauses, silences and response lag during an interaction. This aspect of communication is also influenced by cultural differences as it is well known that there is a great difference in the value given by different cultures to time. #* Kinesics mainly deals with body language such as postures, gestures, head nods, leg movements, etc. In different countries, the same gestures and postures are used to convey different messages. Sometimes even a particular kinesic indicating something good in a country may have a negative meaning in another culture. So in order to have an effective communication across the world it is desirable to have a knowledge of cultural variables effecting communication. According to Michael Walsh and Ghil'ad Zuckermann, Western conversational interaction is typically "dyadic", between two particular people, where eye contact is important and the speaker controls the interaction; and "contained" in a relatively short, defined time frame. However, traditional Aboriginal conversational interaction is "communal", broadcast to many people, eye contact is not important, the listener controls the interaction; and "continuous", spread over a longer, indefinite time frame. Nonhuman Every information exchange between living organisms — i.e. transmission of signals that involve a living sender and receiver can be considered a form of communication; and even primitive creatures such as corals are competent to communicate. Nonhuman communication also include cell signaling, cellular communication, and chemical transmissions between primitive organisms like bacteria and within the plant and fungal kingdoms. =Animals= The broad field of animal communication encompasses most of the issues in ethology. Animal communication can be defined as any behavior of one animal that affects the current or future behavior of another animal. The study of animal communication, called zoo semiotics (distinguishable from anthroposemiotics, the study of human communication) has played an important part in the development of ethology, sociobiology, and the study of animal cognition. Animal communication, and indeed the understanding of the animal world in general, is a rapidly growing field, and even in the 21st century so far, a great share of prior understanding related to diverse fields such as personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, has been revolutionized. =Plants and fungi= Communication is observed within the plant organism, i.e. within plant cells and between plant cells, between plants of the same or related species, and between plants and non-plant organisms, especially in the root zone. Plant roots communicate with rhizome bacteria, fungi, and insects within the soil. Recent research has shown that most of the microorganism plant communication processes are neuron-like. Plants also communicate via volatiles when exposed to herbivory attack behavior, thus warning neighboring plants. In parallel they produce other volatiles to attract parasites which attack these herbivores. Fungi communicate to coordinate and organize their growth and development such as the formation of Marcelia and fruiting bodies. Fungi communicate with their own and related species as well as with non fungal organisms in a great variety of symbiotic interactions, especially with bacteria, unicellular eukaryote, plants and insects through biochemicals of biotic origin. The biochemicals trigger the fungal organism to react in a specific manner, while if the same chemical molecules are not part of biotic messages, they do not trigger the fungal organism to react. This implies that fungal organisms can differentiate between molecules taking part in biotic messages and similar molecules being irrelevant in the situation. So far five different primary signalling molecules are known to coordinate different behavioral patterns such as filamentation, mating, growth, and pathogenicity. Behavioral coordination and production of signaling substances is achieved through interpretation processes that enables the organism to differ between self or non-self, a biotic indicator, biotic message from similar, related, or non-related species, and even filter out "noise", i.e. similar molecules without biotic content. =Bacteria quorum sensing= Communication is not a tool used only by humans, plants and animals, but it is also used by microorganisms like bacteria. The process is called quorum sensing. Through quorum sensing, bacteria can sense the density of cells, and regulate gene expression accordingly. This can be seen in both gram positive and gram negative bacteria. This was first observed by Fuqua et al. in marine microorganisms like V. harveyi and V. fischeri.Anand, Sandhya. Quorum Sensing- Communication Plan For Microbes. Article dated 2010-12-28, retrieved on 2012-04-03. Models upright=1.25 upright=1.25 upright=1.25 upright=1.25 upright=1.25 upright=1.25 upright=1.25 The first major model for communication was introduced by Claude Shannon and Warren Weaver for Bell Laboratories in 1949Shannon, C.E., & Weaver, W. (1949). The mathematical theory of communication. Urbana, Illinois: University of Illinois Press The original model was designed to mirror the functioning of radio and telephone technologies. Their initial model consisted of three primary parts: sender, channel, and receiver. The sender was the part of a telephone a person spoke into, the channel was the telephone itself, and the receiver was the part of the phone where one could hear the other person. Shannon and Weaver also recognized that often there is static that interferes with one listening to a telephone conversation, which they deemed noise. In a simple model, often referred to as the transmission model or standard view of communication, information or content (e.g. a message in natural language) is sent in some form (as spoken language) from an emitter (emisor in the picture)/sender/encoder to a destination/receiver/decoder. This common conception of communication simply views communication as a means of sending and receiving information. The strengths of this model are simplicity, generality, and quantifiability. Claude Shannon and Warren Weaver structured this model based on the following elements: # An information source, which produces a message. # A transmitter, which encodes the message into signals. # A channel, to which signals are adapted for transmission. # A noise source, which distorts the signal while it propagates through the channel. # A receiver, which 'decodes' (reconstructs) the message from the signal. # A destination, where the message arrives. Shannon and Weaver argued that there were three levels of problems for communication within this theory. : The technical problem: how accurately can the message be transmitted? : The semantic problem: how precisely is the meaning conveyed? : The effectiveness problem: how effectively does the received meaning affect behavior? Daniel ChandlerDaniel Chandler, "The Transmission Model of Communication", Aber.ac.uk critiques the transmission model by stating: : It assumes communicators are isolated individuals. : No allowance for differing purposes. : No allowance for differing interpretations. : No allowance for unequal power relations. : No allowance for situational contexts. In 1960, David Berlo expanded on Shannon and Weaver's (1949) linear model of communication and created the SMCR Model of Communication.Berlo, D.K. (1960). The process of communication. New York: Holt, Rinehart & Winston. The Sender-Message-Channel-Receiver Model of communication separated the model into clear parts and has been expanded upon by other scholars. Communication is usually described along a few major dimensions: message (what type of things are communicated), source/emisor/sender/encoder (from whom), form (in which form), channel (through which medium), destination/receiver/target/decoder (to whom). Wilbur Schram (1954) also indicated that we should also examine the impact that a message has (both desired and undesired) on the target of the message.Schramm, W. (1954). How communication works. In W. Schramm (Ed.), The process and effects of communication (pp. 3–26). Urbana, Illinois: University of Illinois Press. Between parties, communication includes acts that confer knowledge and experiences, give advice and commands, and ask questions. These acts may take many forms, in one of the various manners of communication. The form depends on the abilities of the group communicating. Together, communication content and form make messages that are sent towards a destination. The target can be oneself, another person or being, another entity (such as a corporation or group of beings). Communication can be seen as processes of information transmission with three levels of semiotic rules: # Pragmatic (concerned with the relations between signs/expressions and their users). # Semantic (study of relationships between signs and symbols and what they represent). # Syntactic (formal properties of signs and symbols). Therefore, communication is social interaction where at least two interacting agents share a common set of signs and a common set of semiotic rules. This commonly held rule in some sense ignores autocommunication, including intrapersonal communication via diaries or self-talk, both secondary phenomena that followed the primary acquisition of communicative competences within social interactions. In light of these weaknesses, Barnlund (2008) proposed a transactional model of communication.Barnlund, D.C. (2008). A transactional model of communication. In. C.D. Mortensen (Eds.), Communication theory (2nd ed., pp. 47–57). New Brunswick, New Jersey: Transaction. The basic premise of the transactional model of communication is that individuals are simultaneously engaging in the sending and receiving of messages. In a slightly more complex form a sender and a receiver are linked reciprocally. This second attitude of communication, referred to as the constitutive model or constructionist view, focuses on how an individual communicates as the determining factor of the way the message will be interpreted. Communication is viewed as a conduit; a passage in which information travels from one individual to another and this information becomes separate from the communication itself. A particular instance of communication is called a speech act. The sender's personal filters and the receiver's personal filters may vary depending upon different regional traditions, cultures, or gender; which may alter the intended meaning of message contents. In the presence of "communication noise" on the transmission channel (air, in this case), reception and decoding of content may be faulty, and thus the speech act may not achieve the desired effect. One problem with this encode-transmit-receive-decode model is that the processes of encoding and decoding imply that the sender and receiver each possess something that functions as a codebook, and that these two code books are, at the very least, similar if not identical. Although something like code books is implied by the model, they are nowhere represented in the model, which creates many conceptual difficulties. Theories of coregulation describe communication as a creative and dynamic continuous process, rather than a discrete exchange of information. Canadian media scholar Harold Innis had the theory that people use different types of media to communicate and which one they choose to use will offer different possibilities for the shape and durability of society. His famous example of this is using ancient Egypt and looking at the ways they built themselves out of media with very different properties stone and papyrus. Papyrus is what he called 'Space Binding'. it made possible the transmission of written orders across space, empires and enables the waging of distant military campaigns and colonial administration. The other is stone and 'Time Binding', through the construction of temples and the pyramids can sustain their authority generation to generation, through this media they can change and shape communication in their society. Noise In any communication model, noise is interference with the decoding of messages sent over the channel by an encoder. There are many examples of noise: * Environmental noise. Noise that physically disrupts communication, such as standing next to loud speakers at a party, or the noise from a construction site next to a classroom making it difficult to hear the professor. * Physiological-impairment noise. Physical maladies that prevent effective communication, such as actual deafness or blindness preventing messages from being received as they were intended. * Semantic noise. Different interpretations of the meanings of certain words. For example, the word "weed" can be interpreted as an undesirable plant in a yard, or as a euphemism for marijuana. * Syntactical noise. Mistakes in grammar can disrupt communication, such as abrupt changes in verb tense during a sentence. * Organizational noise. Poorly structured communication can prevent the receiver from accurate interpretation. For example, unclear and badly stated directions can make the receiver even more lost. * Cultural noise. Stereotypical assumptions can cause misunderstandings, such as unintentionally offending a non-Christian person by wishing them a "Merry Christmas". * Psychological noise. Certain attitudes can also make communication difficult. For instance, great anger or sadness may cause someone to lose focus on the present moment. Disorders such as autism may also severely hamper effective communication.Roy M. Berko, et al., Communicating. 11th ed. (Boston, MA: Pearson Education, Inc., 2010) 9–12 To face communication noise, redundancy and acknowledgement must often be used. Acknowledgements are messages from the addressee informing the originator that his/her communication has been received and is understood.North Atlantic Treaty Organization, Nato Standardization Agency AAP-6 – Glossary of terms and definitions, p. 43. Message repetition and feedback about message received are necessary in the presence of noise to reduce the probability of misunderstanding. The act of disambiguation regards the attempt of reducing noise and wrong interpretations, when the semantic value or meaning of a sign can be subject to noise, or in presence of multiple meanings, which makes the sense-making difficult. Disambiguation attempts to decrease the likelihood of misunderstanding. This is also a fundamental skill in communication processes activated by counselors, psychotherapists, interpreters, and in coaching sessions based on colloquium. In Information Technology, the disambiguation process and the automatic disambiguation of meanings of words and sentences has also been an interest and concern since the earliest days of computer treatment of language.Nancy Ide, Jean Véronis. "Word Sense Disambiguation: The State of the Art", Computational Linguistics, 24(1), 1998, pp. 1–40. As academic discipline The academic discipline that deals with processes of human communication is communication studies. The discipline encompasses a range of topics, from face-to-face conversation to mass media outlets such as television broadcasting. Communication studies also examines how messages are interpreted through the political, cultural, economic, semiotic, hermeneutic, and social dimensions of their contexts. Statistics, as a quantitative approach to communication science, has also been incorporated into research on communication science in order to help substantiate claims. See alsoReferencesFurther reading * External links Plant cognition Scoutcraft "

❤️ Classics 🐲

"Classics or classical studies is the study of classical antiquity, and in the Western world traditionally refers to the study of Classical Greek and Roman literature in their original languages of Ancient Greek and Latin, respectively. It may also include Greco-Roman philosophy, history, and archaeology as secondary subjects. In Western civilization, the study of the Greek and Roman classics was traditionally considered to be the foundation of the humanities, and study of classics has therefore traditionally been the cornerstone of a typical elite European education. Etymology The word classics is derived from the Latin adjective classicus, meaning "belonging to the highest class of citizens." The word was originally used to describe the members of the highest class in ancient Rome. By the 2nd century AD the word was used in literary criticism to describe writers of the highest quality. For example, Aulus Gellius, in his Attic Nights, contrasts "classicus" and "proletarius" writers.Aulus Gellius, Noctes Atticae, 19.8.15. By the 6th century AD, the word had acquired a second meaning, referring to pupils at a school. Thus, the two modern meanings of the word, referring both to literature considered to be of the highest quality, and to the standard texts used as part of a curriculum, both derive from Roman use. History=Middle Ages= The Roman poet Catullus was virtually unknown during the medieval period, in contrast to his modern popularity. In the Middle Ages, classics and education were tightly intertwined; according to Jan Ziolkowski, there is no era in history in which the link was tighter. Medieval education taught students to imitate earlier classical models, and Latin continued to be the language of scholarship and culture, despite the increasing difference between literary Latin and the vernacular languages of Europe during the period. While Latin was hugely influential, however, Greek was barely studied, and Greek literature survived almost solely in Latin translation. The works of even major Greek authors such as Hesiod, whose names continued to be known by educated Europeans, were unavailable in the Middle Ages. In the thirteenth century, the English philosopher Roger Bacon wrote that "there are not four men in Latin Christendom who are acquainted with the Greek, Hebrew, and Arabic grammars." Along with the unavailability of Greek authors, there were other differences between the classical canon known today and the works valued in the Middle Ages. Catullus, for instance, was almost entirely unknown in the medieval period. The popularity of different authors also waxed and waned throughout the period: Lucretius, popular during the Carolingian period, was barely read in the twelfth century, while for Quintilian the reverse is true. =Renaissance= The Renaissance led to the increasing study of both ancient literature and ancient history, as well as a revival of classical styles of Latin. From the 14th century, first in Italy and then increasingly across Europe, Renaissance Humanism, an intellectual movement that "advocated the study and imitation of classical antiquity", developed. Humanism saw a reform in education in Europe, introducing a wider range of Latin authors as well as bringing back the study of Greek language and literature to Western Europe. This reintroduction was initiated by Petrarch (1304–1374) and Boccaccio (1313–1375) who commissioned a Calabrian scholar to translate the Homeric poems.Pade, M. (2007). The Reception of Plutarch's Lives in Fifteenth-Century Italy. Copenhagen: Museum Tusculanum This humanist educational reform spread from Italy, in Catholic countries as it was adopted by the Jesuits, and in countries that became Protestant such as England, Germany, and the Low Countries, in order to ensure that future clerics were able to study the New Testament in the original language. =Neoclassicism= The late 17th and 18th centuries are the period in Western European literary history which is most associated with the classical tradition, as writers consciously adapted classical models. Classical models were so highly prized that the plays of William Shakespeare were rewritten along neoclassical lines, and these "improved" versions were performed throughout the 18th century. From the beginning of the 18th century, the study of Greek became increasingly important relative to that of Latin. In this period Johann Winckelmann's claims for the superiority of the Greek visual arts influenced a shift in aesthetic judgements, while in the literary sphere, G.E. Lessing "returned Homer to the centre of artistic achievement". In the United Kingdom, the study of Greek in schools began in the late 18th century. The poet Walter Savage Landor claimed to have been one of the first English schoolboys to write in Greek during his time at Rugby School. =19th century= The 19th century saw the influence of the classical world, and the value of a classical education, decline, especially in the US, where the subject was often criticised for its elitism. By the 19th century, little new literature was still being written in Latin – a practice which had continued as late as the 18th century – and a command of Latin declined in importance. Correspondingly, classical education from the 19th century onwards began to increasingly de-emphasise the importance of the ability to write and speak Latin. In the United Kingdom this process took longer than elsewhere. Composition continued to be the dominant classical skill in England until the 1870s, when new areas within the discipline began to increase in popularity. In the same decade came the first challenges to the requirement of Greek at the universities of Oxford and Cambridge, though it would not be finally abolished for another 50 years. Though the influence of classics as the dominant mode of education in Europe and North America was in decline in the 19th century, the discipline was rapidly evolving in the same period. Classical scholarship was becoming more systematic and scientific, especially with the "new philology" created at the end of the 18th and beginning of the 19th century. Its scope was also broadening: it was during the 19th century that ancient history and classical archaeology began to be seen as part of classics rather than separate disciplines. =20th century to present= During the 20th century, the study of classics became less common. In England, for instance, Oxford and Cambridge universities stopped requiring students to have qualifications in Greek in 1920, and in Latin at the end of the 1950s. When the National Curriculum was introduced in England, Wales, and Northern Ireland in 1988, it did not mention the classics. By 2003, only about 10% of state schools in Britain offered any classical subjects to their students at all. In 2016, AQA, the largest exam board for A-Levels and GCSE's in England, Wales and Northern Ireland, announced that it would be scrapping A-Level subjects in Classical Civilization, Archaeology, and Art History. This left just one out of five exam boards in England which still offered Classical Civilization as a subject. The decision was immediately denounced by archaeologists and historians, with Natalie Haynes of the Guardian stating that the loss of the A-Level would deprive state school students, 93% of all students, the opportunity to study classics while making it once again the exclusive purview of wealthy private-school students. However, the study of classics has not declined as fast elsewhere in Europe. In 2009, a review of Meeting the Challenge, a collection of conference papers about the teaching of Latin in Europe, noted that though there is opposition to the teaching of Latin in Italy, it is nonetheless still compulsory in most secondary schools. The same can be said in the case of France or Greece, too. Indeed, Ancient Greek is one of the compulsory subjects in Greek secondary education, whereas in France, Latin is one of the optional subjects that can be chosen in a majority of middle schools and high schools. Ancient Greek is also still being taught, but not as much as Latin. Sub-disciplines One of the most notable characteristics of the modern study of classics is the diversity of the field. Although traditionally focused on ancient Greece and Rome, the study now encompasses the entire ancient Mediterranean world, thus expanding the studies to Northern Africa as well as parts of the Middle East. =Philology= The eighteenth-century classicist Friedrich August Wolf was the author of Prolegomena to Homer, one of the first great works of classical philology. Philology is the study of language preserved in written sources; classical philology is thus concerned with understanding any texts from the classical period written in the classical languages of Latin and Greek. The roots of classical philology lie in the Renaissance, as humanist intellectuals attempted to return to the Latin of the classical period, especially of Cicero, and as scholars attempted to produce more accurate editions of ancient texts. Some of the principles of philology still used today were developed during this period, for instance, the observation that if a manuscript could be shown to be a copy of an earlier extant manuscript, then it provides no further evidence of the original text, was made as early as 1489 by Angelo Poliziano. Other philological tools took longer to be developed: the first statement, for instance, of the principle that a more difficult reading should be preferred over a simpler one, was in 1697 by Jean Le Clerc. The modern discipline of classical philology began in Germany at the turn of the nineteenth century. It was during this period that scientific principles of philology began to be put together into a coherent whole, in order to provide a set of rules by which scholars could determine which manuscripts were most accurate. This "new philology", as it was known, centred around the construction of a genealogy of manuscripts, with which a hypothetical common ancestor, closer to the original text than any existing manuscript, could be reconstructed. =Archaeology= Schliemann and Dörpfeld's excavation at Mycenae was one of the earliest excavations in the field of classical archaeology. Classical archaeology is the oldest branch of archaeology, with its roots going back to J.J. Winckelmann's work on Herculaneum in the 1760s. It was not until the last decades of the 19th century, however, that classical archaeology became part of the tradition of Western classical scholarship. It was included as part of Cambridge University's Classical Tripos for the first time after the reforms of the 1880s, though it did not become part of Oxford's Greats until much later. The second half of the 19th century saw Schliemann's excavations of Troy and Mycenae; the first excavations at Olympia and Delos; and Arthur Evans' work in Crete, particularly on Knossos. This period also saw the foundation of important archaeological associations (e.g. the Archaeological Institute of America in 1879), including many foreign archaeological institutes in Athens and Rome (the American School of Classical Studies at Athens in 1881, British School at Athens in 1886, American Academy in Rome in 1895, and British School at Rome in 1900). More recently, classical archaeology has taken little part in the theoretical changes in the rest of the discipline, largely ignoring the popularity of "New Archaeology", which emphasised the development of general laws derived from studying material culture, in the 1960s. New Archaeology is still criticized by traditional minded scholars of classical archaeology despite a wide acceptance of its basic techniques. =Art history= Some art historians focus their study on the development of art in the classical world. Indeed, the art and architecture of Ancient Rome and Greece is very well regarded and remains at the heart of much of our art today. For example, Ancient Greek architecture gave us the Classical Orders: Doric, Ionic, and Corinthian. The Parthenon is still the architectural symbol of the classical world. Greek sculpture is well known and we know the names of several Ancient Greek artists: for example, Phidias. =Ancient history= With philology, archaeology, and art history, scholars seek understanding of the history and culture of a civilisation, through critical study of the extant literary and physical artefacts, in order to compose and establish a continual historic narrative of the Ancient World and its peoples. The task is difficult due to a dearth of physical evidence: for example, Sparta was a leading Greek city-state, yet little evidence of it survives to study, and what is available comes from Athens, Sparta's principal rival; likewise, the Roman Empire destroyed most evidence (cultural artefacts) of earlier, conquered civilizations, such as that of the Etruscans. =Philosophy= The English word "philosophy" comes from the Greek word φιλοσοφία, meaning "love of wisdom", probably coined by Pythagoras. Along with the word itself, the discipline of philosophy as we know it today has its roots in ancient Greek thought, and according to Martin West "philosophy as we understand it is a Greek creation". Ancient philosophy was traditionally divided into three branches: logic, physics, and ethics. However, not all of the works of ancient philosophers fit neatly into one of these three branches. For instance, Aristotle's Rhetoric and Poetics have been traditionally classified in the West as "ethics", but in the Arabic world were grouped with logic; in reality, they do not fit neatly into either category. From the last decade of the eighteenth century, scholars of ancient philosophy began to study the discipline historically. Previously, works on ancient philosophy had been unconcerned with chronological sequence and with reconstructing the reasoning of ancient thinkers; with what Wolfgang-Ranier Mann calls "New Philosophy", this changed. =Reception studies= A relatively recent new discipline within the classics is "reception studies", which developed in the 1960s at the University of Konstanz. Reception studies is concerned with how students of classical texts have understood and interpreted them. As such, reception studies is interested in a two-way interaction between reader and text, taking place within a historical context. Though the idea of an "aesthetics of reception" was first put forward by Hans Robert Jauss in 1967, the principles of reception theory go back much earlier than this. As early as 1920, T. S. Eliot wrote that "the past [is] altered by the present as much as the present is directed by the past"; Charles Martindale describes this as a "cardinal principle" for many versions of modern reception theory. Classical Greece Ancient Greece was the civilization belonging to the period of Greek history lasting from the Archaic period, beginning in the eighth century BC, to the Roman conquest of Greece after the Battle of Corinth in 146 BC. The Classical period, during the fifth and fourth centuries BC, has traditionally been considered the height of Greek civilisation. The Classical period of Greek history is generally considered to have begun with the first and second Persian invasions of Greece at the start of the Greco-Persian wars, and to have ended with the death of Alexander the Great. Classical Greek culture had a powerful influence on the Roman Empire, which carried a version of it to many parts of the Mediterranean region and Europe; thus Classical Greece is generally considered to be the seminal culture which provided the foundation of Western civilization. =Language= Map showing the regional dialects of Greek during the Classical period Ancient Greek is the historical stage in the development of the Greek language spanning the Archaic (c. 8th to 6th centuries BC), Classical (c. 5th to 4th centuries BC), and Hellenistic (c. 3rd century BC to 6th century AD) periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek. Its Hellenistic phase is known as Koine ("common") or Biblical Greek, and its late period mutates imperceptibly into Medieval Greek. Koine is regarded as a separate historical stage of its own, although in its earlier form it closely resembles Classical Greek. Prior to the Koine period, Greek of the classical and earlier periods included several regional dialects. Ancient Greek was the language of Homer and of classical Athenian historians, playwrights, and philosophers. It has contributed many words to the vocabulary of English and many other European languages, and has been a standard subject of study in Western educational institutions since the Renaissance. Latinized forms of Ancient Greek roots are used in many of the scientific names of species and in other scientific terminology. =Literature= The earliest surviving works of Greek literature are epic poetry. Homer's Iliad and Odyssey are the earliest to survive to us today, probably composed in the eighth century BC. These early epics were oral compositions, created without the use of writing. Around the same time that the Homeric epics were composed, the Greek alphabet was introduced; the earliest surviving inscriptions date from around 750 BC. European drama was invented in ancient Greece. Traditionally this was attributed to Thespis, around the middle of the sixth century BC, though the earliest surviving work of Greek drama is Aeschylus' tragedy The Persians, which dates to 472 BC. Early Greek tragedy was performed by a chorus and two actors, but by the end of Aeschylus' life, a third actor had been introduced, either by him or by Sophocles. The last surviving Greek tragedies are the Bacchae of Euripides and Sophocles' Oedipus at Colonus, both from the end of the fifth century BC. Surviving Greek comedy begins later than tragedy; the earliest surviving work, Aristophanes' Acharnians, comes from 425 BC. However, comedy dates back as early as 486 BC, when the Dionysia added a competition for comedy to the much earlier competition for tragedy. The comedy of the fifth century is known as Old Comedy, and it comes down to us solely in the eleven surviving plays of Aristophanes, along with a few fragments. Sixty years after the end of Aristophanes' career, the next author of comedies to have any substantial body of work survive is Menander, whose style is known as New Comedy. Two historians flourished during Greece's classical age: Herodotus and Thucydides. Herodotus is commonly called the father of history, and his "History" contains the first truly literary use of prose in Western literature. Of the two, Thucydides was the more careful historian. His critical use of sources, inclusion of documents, and laborious research made his History of the Peloponnesian War a significant influence on later generations of historians. The greatest achievement of the 4th century was in philosophy. There were many Greek philosophers, but three names tower above the rest: Socrates, Plato, and Aristotle. These have had a profound influence on Western society. =Mythology and religion= Greek mythology is the body of myths and legends belonging to the ancient Greeks concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece. Modern scholars refer to the myths and study them in an attempt to throw light on the religious and political institutions of Ancient Greece and its civilization, and to gain understanding of the nature of myth-making itself. Greek religion encompassed the collection of beliefs and rituals practiced in ancient Greece in the form of both popular public religion and cult practices. These different groups varied enough for it to be possible to speak of Greek religions or "cults" in the plural, though most of them shared similarities. Also, the Greek religion extended out of Greece and out to neighbouring islands. Many Greek people recognized the major gods and goddesses: Zeus, Poseidon, Hades, Apollo, Artemis, Aphrodite, Ares, Dionysus, Hephaestus, Athena, Hermes, Demeter, Hestia and Hera; though philosophies such as Stoicism and some forms of Platonism used language that seems to posit a transcendent single deity. Different cities often worshipped the same deities, sometimes with epithets that distinguished them and specified their local nature. =Philosophy= So influential was Socrates to classical philosophy that earlier philosophers are today known as pre-Socratics. The earliest surviving philosophy from ancient Greece dates back to the 6th century BC, when according to Aristotle Thales of Miletus was considered to have been the first Greek philosopher.Aristotle, Metaphysics Alpha, 983b18. Other influential pre- Socratic philosophers include Pythagoras and Heraclitus. The most famous and significant figures in classical Athenian philosophy, from the 5th to the 3rd centuries BC, are Socrates, his student Plato, and Aristotle, who studied at Plato's Academy before founding his own school, known as the Lyceum. Later Greek schools of philosophy, including the Cynics, Stoics, and Epicureans, continued to be influential after the Roman annexation of Greece, and into the post-Classical world. Greek philosophy dealt with a wide variety of subjects, including political philosophy, ethics, metaphysics, ontology, and logic, as well as disciplines which are not today thought of as part of philosophy, such as biology and rhetoric. Classical Rome=Language= The Praeneste fibula is believed to bear the oldest known Latin inscription. The inscription means "Manius made me for Numerius". The language of ancient Rome was Latin, a member of the Italic family of languages. The earliest surviving inscription in Latin comes from the 7th century BC, on a brooch from Palestrina. Latin from between this point and the early 1st century BC is known as Old Latin. Most surviving Latin literature is Classical Latin, from the 1st century BC to the 2nd century AD. Latin then evolved into Late Latin, in use during the late antique period. Late Latin survived long after the end of classical antiquity, and was finally replaced by written Romance languages around the 9th century AD. Along with literary forms of Latin, there existed various vernacular dialects, generally known as Vulgar Latin, in use throughout antiquity. These are mainly preserved in sources such as graffiti and the Vindolanda tablets. =Literature= The earliest surviving Latin authors, writing in Old Latin, include the playwrights Plautus and Terence. Much of the best known and most highly thought of Latin literature comes from the classical period, with poets such as Virgil, Horace, and Ovid; historians such as Julius Caesar and Tacitus; orators such as Cicero; and philosophers such as Seneca the Younger and Lucretius. Late Latin authors include many Christian writers such as Lactantius, Tertullian and Ambrose; non-Christian authors, such as the historian Ammianus Marcellinus, are also preserved. =History= According to legend, the city of Rome was founded in 753 BC; in reality, there had been a settlement on the site since around 1000 BC, when the Palatine Hill was settled. The city was originally ruled by kings, first Roman, and then Etruscan – according to Roman tradition, the first Etruscan king of Rome, Tarquinius Priscus, ruled from 616 BC. Over the course of the 6th century BC, the city expanded its influence over the entirety of Latium. Around the end of the 6th century – traditionally in 510 BC – the kings of Rome were driven out, and the city became a republic. Around 387 BC, Rome was sacked by the Gauls following the Battle of the Allia. It soon recovered from this humiliating defeat, however, and in 381 the inhabitants of Tusculum in Latium were made Roman citizens. This was the first time Roman citizenship was extended in this way. Rome went on to expand its area of influence, until by 269 the entirety of the Italian peninsula was under Roman rule. Soon afterwards, in 264, the First Punic War began; it lasted until 241. The Second Punic War began in 218, and by the end of that year, the Carthaginian general Hannibal had invaded Italy. The war saw Rome's worst defeat to that point at Cannae; the largest army Rome had yet put into the field was wiped out, and one of the two consuls leading it was killed. However, Rome continued to fight, annexing much of Spain and eventually defeating Carthage, ending her position as a major power and securing Roman preeminence in the Western Mediterranean. Legacy of the classical world The classical languages of the Ancient Mediterranean world influenced every European language, imparting to each a learned vocabulary of international application. Thus, Latin grew from a highly developed cultural product of the Golden and Silver eras of Latin literature to become the international lingua franca in matters diplomatic, scientific, philosophic and religious, until the 17th century. Long before this, Latin had evolved into the Romance languages and Ancient Greek into Modern Greek and its dialects. In the specialised science and technology vocabularies, the influence of Latin and Greek is notable. Ecclesiastical Latin, the Roman Catholic Church's official language, remains a living legacy of the classical world in the contemporary world. Latin had an impact far beyond the classical world. It continued to be the pre-eminent language for serious writings in Europe long after the fall of the Roman empire. The modern Romance languages – such as French, Spanish, and Italian – all derive from Latin. Latin is still seen as a foundational aspect of European culture. The legacy of the classical world is not confined to the influence of classical languages. The Roman empire was taken as a model by later European empires, such as the Spanish and British empires. Classical art has been taken as a model in later periods – medieval Romanesque architecture and Enlightenment-era neoclassical literature were both influenced by classical models, to take but two examples, while Joyce's Ulysses is one of the most influential works of twentieth century literature. See also * Classical tradition * Great Books of the Western World * Neoclassicism * Outline of classical studies * Outline of ancient Greece * Outline of ancient Rome References = Citations Sources = ; Works cited Further reading ;;General ;;Philology * ;;Greek history ;;Roman history ;;Literature * ;;Philosophy ;;Art and archaeology * External links * Classical Resources on Internet at the Department of Classical Philology, University of Tartu. * Electronic Resources for Classicists by the University of California, Irvine. * Illustrated History of the Roman Empire * The Perseus Digital Library * The Alpheios Project Ancient Greece Study of ancient Rome Humanities "

❤️ Chemistry 🐲

"An oil painting of a chemist (by Henrika Šantel in 1932) Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances. In the scope of its subject, chemistry occupies an intermediate position between physics and biology.Carsten Reinhardt. Chemical Sciences in the 20th Century: Bridging Boundaries. Wiley-VCH, 2001. . pp. 1–2. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level.Theodore L. Brown, H. Eugene Lemay, Bruce Edward Bursten, H. Lemay. Chemistry: The Central Science. Prentice Hall; 8 edition (1999). . pp. 3–4. For example, chemistry explains aspects of plant chemistry (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the moon (cosmochemistry), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics). Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron(s); ionic bonds, in which a compound donates one or more electrons to another compound to produce ions (cations and anions); hydrogen bonds; and Van der Waals force bonds. Etymology The word chemistry comes from alchemy, which referred to an earlier set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine. It is often seen as linked to the quest to turn lead or another common starting material into gold, though in ancient times, the study encompassed many of the questions of modern chemistry being defined as the study of the composition of waters, movement, growth, embodying, disembodying, drawing the spirits from bodies and bonding the spirits within bodies by the early 4th century Greek-Egyptian alchemist Zosimos.Strathern, P. (2000). Mendeleyev's Dream – the Quest for the Elements. New York: Berkley Books. An alchemist was called a 'chemist' in popular speech, and later the suffix "-ry" was added to this to describe the art of the chemist as "chemistry". The modern word alchemy in turn is derived from the Arabic word al-kīmīā (الكیمیاء). In origin, the term is borrowed from the Greek χημία or χημεία."alchemy", entry in The Oxford English Dictionary, J.A. Simpson and E.S.C. Weiner, vol. 1, 2nd ed., 1989, .p. 854, "Arabic alchemy", Georges C. Anawati, pp. 853–885 in Encyclopedia of the history of Arabic science, eds. Roshdi Rashed and Régis Morelon, London: Routledge, 1996, vol. 3, . This may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Kemet, which is the ancient name of Egypt in the Egyptian language. Alternately, al-kīmīā may derive from χημεία, meaning "cast together".Weekley, Ernest (1967). Etymological Dictionary of Modern English. New York: Dover Publications. Modern principles Laboratory, Institute of Biochemistry, University of Cologne in Germany. The current model of atomic structure is the quantum mechanical model. Traditional chemistry starts with the study of elementary particles, atoms, molecules,Matter: Atoms from Democritus to Dalton by Anthony Carpi, Ph.D. substances, metals, crystals and other aggregates of matter. Matter can be studied in solid, liquid, gas and plasma states, in isolation or in combination. The interactions, reactions and transformations that are studied in chemistry are usually the result of interactions between atoms, leading to rearrangements of the chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory. The chemistry laboratory stereotypically uses various forms of laboratory glassware. However glassware is not central to chemistry, and a great deal of experimental (as well as applied/industrial) chemistry is done without it. Solutions of substances in reagent bottles, including ammonium hydroxide and nitric acid, illuminated in different colors A chemical reaction is a transformation of some substances into one or more different substances.IUPAC Gold Book Definition The basis of such a chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation, which usually involves atoms as subjects. The number of atoms on the left and the right in the equation for a chemical transformation is equal. (When the number of atoms on either side is unequal, the transformation is referred to as a nuclear reaction or radioactive decay.) The type of chemical reactions a substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws. Energy and entropy considerations are invariably important in almost all chemical studies. Chemical substances are classified in terms of their structure, phase, as well as their chemical compositions. They can be analyzed using the tools of chemical analysis, e.g. spectroscopy and chromatography. Scientists engaged in chemical research are known as chemists. Most chemists specialize in one or more sub-disciplines. Several concepts are essential for the study of chemistry; some of them are: =Matter= In chemistry, matter is defined as anything that has rest mass and volume (it takes up space) and is made up of particles. The particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon. Matter can be a pure chemical substance or a mixture of substances. Atom A diagram of an atom based on the Bohr model The atom is the basic unit of chemistry. It consists of a dense core called the atomic nucleus surrounded by a space occupied by an electron cloud. The nucleus is made up of positively charged protons and uncharged neutrons (together called nucleons), while the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons. The nucleus is dense; the mass of a nucleon is approximately 1,836 times that of an electron, yet the radius of an atom is about 10,000 times that of its nucleus. The atom is also the smallest entity that can be envisaged to retain the chemical properties of the element, such as electronegativity, ionization potential, preferred oxidation state(s), coordination number, and preferred types of bonds to form (e.g., metallic, ionic, covalent). Element Standard form of the periodic table of chemical elements. The colors represent different categories of elements A chemical element is a pure substance which is composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z. The mass number is the sum of the number of protons and neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same atomic number, they may not necessarily have the same mass number; atoms of an element which have different mass numbers are known as isotopes. For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon, but atoms of carbon may have mass numbers of 12 or 13. The standard presentation of the chemical elements is in the periodic table, which orders elements by atomic number. The periodic table is arranged in groups, or columns, and periods, or rows. The periodic table is useful in identifying periodic trends. Compound Carbon dioxide (CO2), an example of a chemical compound A compound is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to the inorganic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In addition the Chemical Abstracts Service has devised a method to index chemical substances. In this scheme each chemical substance is identifiable by a number known as its CAS registry number. Molecule A ball-and-stick representation of the caffeine molecule (C8H10N4O2). A molecule is the smallest indivisible portion of a pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for substances that are composed of molecules, which is not true of many substances (see below). Molecules are typically a set of atoms bound together by covalent bonds, such that the structure is electrically neutral and all valence electrons are paired with other electrons either in bonds or in lone pairs. Thus, molecules exist as electrically neutral units, unlike ions. When this rule is broken, giving the "molecule" a charge, the result is sometimes named a molecular ion or a polyatomic ion. However, the discrete and separate nature of the molecular concept usually requires that molecular ions be present only in well-separated form, such as a directed beam in a vacuum in a mass spectrometer. Charged polyatomic collections residing in solids (for example, common sulfate or nitrate ions) are generally not considered "molecules" in chemistry. Some molecules contain one or more unpaired electrons, creating radicals. Most radicals are comparatively reactive, but some, such as nitric oxide (NO) can be stable. A 2-D structural formula of a benzene molecule (C6H6) The "inert" or noble gas elements (helium, neon, argon, krypton, xenon and radon) are composed of lone atoms as their smallest discrete unit, but the other isolated chemical elements consist of either molecules or networks of atoms bonded to each other in some way. Identifiable molecules compose familiar substances such as water, air, and many organic compounds like alcohol, sugar, gasoline, and the various pharmaceuticals. However, not all substances or chemical compounds consist of discrete molecules, and indeed most of the solid substances that make up the solid crust, mantle, and core of the Earth are chemical compounds without molecules. These other types of substances, such as ionic compounds and network solids, are organized in such a way as to lack the existence of identifiable molecules per se. Instead, these substances are discussed in terms of formula units or unit cells as the smallest repeating structure within the substance. Examples of such substances are mineral salts (such as table salt), solids like carbon and diamond, metals, and familiar silica and silicate minerals such as quartz and granite. One of the main characteristics of a molecule is its geometry often called its structure. While the structure of diatomic, triatomic or tetra-atomic molecules may be trivial, (linear, angular pyramidal etc.) the structure of polyatomic molecules, that are constituted of more than six atoms (of several elements) can be crucial for its chemical nature. Substance and mixture A chemical substance is a kind of matter with a definite composition and set of properties. A collection of substances is called a mixture. Examples of mixtures are air and alloys. Mole and amount of substance The mole is a unit of measurement that denotes an amount of substance (also called chemical amount). One mole is defined to contain exactly particles (atoms, molecules, ions, or electrons), where the number of particles per mole is known as the Avogadro constant. Molar concentration is the amount of a particular substance per volume of solution, and is commonly reported in mol/dm3. =Phase= Diagram showing relationships among the phases and the terms used to describe phase changes. In addition to the specific chemical properties that distinguish different chemical classifications, chemicals can exist in several phases. For the most part, the chemical classifications are independent of these bulk phase classifications; however, some more exotic phases are incompatible with certain chemical properties. A phase is a set of states of a chemical system that have similar bulk structural properties, over a range of conditions, such as pressure or temperature. Physical properties, such as density and refractive index tend to fall within values characteristic of the phase. The phase of matter is defined by the phase transition, which is when energy put into or taken out of the system goes into rearranging the structure of the system, instead of changing the bulk conditions. Sometimes the distinction between phases can be continuous instead of having a discrete boundary' in this case the matter is considered to be in a supercritical state. When three states meet based on the conditions, it is known as a triple point and since this is invariant, it is a convenient way to define a set of conditions. The most familiar examples of phases are solids, liquids, and gases. Many substances exhibit multiple solid phases. For example, there are three phases of solid iron (alpha, gamma, and delta) that vary based on temperature and pressure. A principal difference between solid phases is the crystal structure, or arrangement, of the atoms. Another phase commonly encountered in the study of chemistry is the aqueous phase, which is the state of substances dissolved in aqueous solution (that is, in water). Less familiar phases include plasmas, Bose–Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology. =Bonding= An animation of the process of ionic bonding between sodium (Na) and chlorine (Cl) to form sodium chloride, or common table salt. Ionic bonding involves one atom taking valence electrons from another (as opposed to sharing, which occurs in covalent bonding) Atoms sticking together in molecules or crystals are said to be bonded with one another. A chemical bond may be visualized as the multipole balance between the positive charges in the nuclei and the negative charges oscillating about them. More than simple attraction and repulsion, the energies and distributions characterize the availability of an electron to bond to another atom. A chemical bond can be a covalent bond, an ionic bond, a hydrogen bond or just because of Van der Waals force. Each of these kinds of bonds is ascribed to some potential. These potentials create the interactions which hold atoms together in molecules or crystals. In many simple compounds, valence bond theory, the Valence Shell Electron Pair Repulsion model (VSEPR), and the concept of oxidation number can be used to explain molecular structure and composition. An ionic bond is formed when a metal loses one or more of its electrons, becoming a positively charged cation, and the electrons are then gained by the non-metal atom, becoming a negatively charged anion. The two oppositely charged ions attract one another, and the ionic bond is the electrostatic force of attraction between them. For example, sodium (Na), a metal, loses one electron to become an Na+ cation while chlorine (Cl), a non-metal, gains this electron to become Cl−. The ions are held together due to electrostatic attraction, and that compound sodium chloride (NaCl), or common table salt, is formed. In the methane molecule (CH4), the carbon atom shares a pair of valence electrons with each of the four hydrogen atoms. Thus, the octet rule is satisfied for C-atom (it has eight electrons in its valence shell) and the duet rule is satisfied for the H-atoms (they have two electrons in their valence shells). In a covalent bond, one or more pairs of valence electrons are shared by two atoms: the resulting electrically neutral group of bonded atoms is termed a molecule. Atoms will share valence electrons in such a way as to create a noble gas electron configuration (eight electrons in their outermost shell) for each atom. Atoms that tend to combine in such a way that they each have eight electrons in their valence shell are said to follow the octet rule. However, some elements like hydrogen and lithium need only two electrons in their outermost shell to attain this stable configuration; these atoms are said to follow the duet rule, and in this way they are reaching the electron configuration of the noble gas helium, which has two electrons in its outer shell. Similarly, theories from classical physics can be used to predict many ionic structures. With more complicated compounds, such as metal complexes, valence bond theory is less applicable and alternative approaches, such as the molecular orbital theory, are generally used. See diagram on electronic orbitals. =Energy= In the context of chemistry, energy is an attribute of a substance as a consequence of its atomic, molecular or aggregate structure. Since a chemical transformation is accompanied by a change in one or more of these kinds of structures, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. A reaction is said to be exothermic if the reaction releases heat to the surroundings; in the case of endothermic reactions, the reaction absorbs heat from the surroundings. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e^{-E/kT} – that is the probability of a molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation. The activation energy necessary for a chemical reaction to occur can be in the form of heat, light, electricity or mechanical force in the form of ultrasound.Reilly, Michael. (2007). Mechanical force induces chemical reaction, NewScientist.com news service, Reilly A related concept free energy, which also incorporates entropy considerations, is a very useful means for predicting the feasibility of a reaction and determining the state of equilibrium of a chemical reaction, in chemical thermodynamics. A reaction is feasible only if the total change in the Gibbs free energy is negative, \Delta G \le 0 \,; if it is equal to zero the chemical reaction is said to be at equilibrium. There exist only limited possible states of energy for electrons, atoms and molecules. These are determined by the rules of quantum mechanics, which require quantization of energy of a bound system. The atoms/molecules in a higher energy state are said to be excited. The molecules/atoms of substance in an excited energy state are often much more reactive; that is, more amenable to chemical reactions. The phase of a substance is invariably determined by its energy and the energy of its surroundings. When the intermolecular forces of a substance are such that the energy of the surroundings is not sufficient to overcome them, it occurs in a more ordered phase like liquid or solid as is the case with water (H2O); a liquid at room temperature because its molecules are bound by hydrogen bonds.Changing States of Matter – Chemforkids.com Whereas hydrogen sulfide (H2S) is a gas at room temperature and standard pressure, as its molecules are bound by weaker dipole-dipole interactions. The transfer of energy from one chemical substance to another depends on the size of energy quanta emitted from one substance. However, heat energy is often transferred more easily from almost any substance to another because the phonons responsible for vibrational and rotational energy levels in a substance have much less energy than photons invoked for the electronic energy transfer. Thus, because vibrational and rotational energy levels are more closely spaced than electronic energy levels, heat is more easily transferred between substances relative to light or other forms of electronic energy. For example, ultraviolet electromagnetic radiation is not transferred with as much efficacy from one substance to another as thermal or electrical energy. The existence of characteristic energy levels for different chemical substances is useful for their identification by the analysis of spectral lines. Different kinds of spectra are often used in chemical spectroscopy, e.g. IR, microwave, NMR, ESR, etc. Spectroscopy is also used to identify the composition of remote objects – like stars and distant galaxies – by analyzing their radiation spectra. Emission spectrum of iron The term chemical energy is often used to indicate the potential of a chemical substance to undergo a transformation through a chemical reaction or to transform other chemical substances. =Reaction= compound, reacts with carbon monoxide to form iron, one of the chemical elements, and carbon dioxide. When a chemical substance is transformed as a result of its interaction with another substance or with energy, a chemical reaction is said to have occurred. A chemical reaction is therefore a concept related to the "reaction" of a substance when it comes in close contact with another, whether as a mixture or a solution; exposure to some form of energy, or both. It results in some energy exchange between the constituents of the reaction as well as with the system environment, which may be designed vessels—often laboratory glassware. Chemical reactions can result in the formation or dissociation of molecules, that is, molecules breaking apart to form two or more molecules or rearrangement of atoms within or across molecules. Chemical reactions usually involve the making or breaking of chemical bonds. Oxidation, reduction, dissociation, acid-base neutralization and molecular rearrangement are some of the commonly used kinds of chemical reactions. A chemical reaction can be symbolically depicted through a chemical equation. While in a non-nuclear chemical reaction the number and kind of atoms on both sides of the equation are equal, for a nuclear reaction this holds true only for the nuclear particles viz. protons and neutrons.Chemical Reaction Equation – IUPAC Goldbook The sequence of steps in which the reorganization of chemical bonds may be taking place in the course of a chemical reaction is called its mechanism. A chemical reaction can be envisioned to take place in a number of steps, each of which may have a different speed. Many reaction intermediates with variable stability can thus be envisaged during the course of a reaction. Reaction mechanisms are proposed to explain the kinetics and the relative product mix of a reaction. Many physical chemists specialize in exploring and proposing the mechanisms of various chemical reactions. Several empirical rules, like the Woodward–Hoffmann rules often come in handy while proposing a mechanism for a chemical reaction. According to the IUPAC gold book, a chemical reaction is "a process that results in the interconversion of chemical species."Gold Book Chemical Reaction IUPAC Goldbook Accordingly, a chemical reaction may be an elementary reaction or a stepwise reaction. An additional caveat is made, in that this definition includes cases where the interconversion of conformers is experimentally observable. Such detectable chemical reactions normally involve sets of molecular entities as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e. 'microscopic chemical events'). =Ions and salts= The crystal lattice structure of potassium chloride (KCl), a salt which is formed due to the attraction of K+ cations and Cl− anions. Note how the overall charge of the ionic compound is zero. An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons. When an atom loses an electron and thus has more protons than electrons, the atom is a positively charged ion or cation. When an atom gains an electron and thus has more electrons than protons, the atom is a negatively charged ion or anion. Cations and anions can form a crystalline lattice of neutral salts, such as the Na+ and Cl− ions forming sodium chloride, or NaCl. Examples of polyatomic ions that do not split up during acid-base reactions are hydroxide (OH−) and phosphate (PO43−). Plasma is composed of gaseous matter that has been completely ionized, usually through high temperature. =Acidity and basicity= Hydrogen bromide exists in the gas phase as a diatomic molecule A substance can often be classified as an acid or a base. There are several different theories which explain acid-base behavior. The simplest is Arrhenius theory, which states that acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water. According to Brønsted–Lowry acid-base theory, acids are substances that donate a positive hydrogen ion to another substance in a chemical reaction; by extension, a base is the substance which receives that hydrogen ion. A third common theory is Lewis acid-base theory, which is based on the formation of new chemical bonds. Lewis theory explains that an acid is a substance which is capable of accepting a pair of electrons from another substance during the process of bond formation, while a base is a substance which can provide a pair of electrons to form a new bond. According to this theory, the crucial things being exchanged are charges. There are several other ways in which a substance may be classified as an acid or a base, as is evident in the history of this concept. Acid strength is commonly measured by two methods. One measurement, based on the Arrhenius definition of acidity, is pH, which is a measurement of the hydronium ion concentration in a solution, as expressed on a negative logarithmic scale. Thus, solutions that have a low pH have a high hydronium ion concentration and can be said to be more acidic. The other measurement, based on the Brønsted–Lowry definition, is the acid dissociation constant (Ka), which measures the relative ability of a substance to act as an acid under the Brønsted–Lowry definition of an acid. That is, substances with a higher Ka are more likely to donate hydrogen ions in chemical reactions than those with lower Ka values. =Redox= Redox (reduction-oxidation) reactions include all chemical reactions in which atoms have their oxidation state changed by either gaining electrons (reduction) or losing electrons (oxidation). Substances that have the ability to oxidize other substances are said to be oxidative and are known as oxidizing agents, oxidants or oxidizers. An oxidant removes electrons from another substance. Similarly, substances that have the ability to reduce other substances are said to be reductive and are known as reducing agents, reductants, or reducers. A reductant transfers electrons to another substance and is thus oxidized itself. And because it "donates" electrons it is also called an electron donor. Oxidation and reduction properly refer to a change in oxidation number—the actual transfer of electrons may never occur. Thus, oxidation is better defined as an increase in oxidation number, and reduction as a decrease in oxidation number. =Equilibrium= Although the concept of equilibrium is widely used across sciences, in the context of chemistry, it arises whenever a number of different states of the chemical composition are possible, as for example, in a mixture of several chemical compounds that can react with one another, or when a substance can be present in more than one kind of phase. A system of chemical substances at equilibrium, even though having an unchanging composition, is most often not static; molecules of the substances continue to react with one another thus giving rise to a dynamic equilibrium. Thus the concept describes the state in which the parameters such as chemical composition remain unchanged over time. =Chemical laws= Chemical reactions are governed by certain laws, which have become fundamental concepts in chemistry. Some of them are: * Avogadro's law * Beer–Lambert law * Boyle's law (1662, relating pressure and volume) * Charles's law (1787, relating volume and temperature) * Fick's laws of diffusion * Gay-Lussac's law (1809, relating pressure and temperature) * Le Chatelier's principle * Henry's law * Hess's law * Law of conservation of energy leads to the important concepts of equilibrium, thermodynamics, and kinetics. * Law of conservation of mass continues to be conserved in isolated systems, even in modern physics. However, special relativity shows that due to mass–energy equivalence, whenever non-material "energy" (heat, light, kinetic energy) is removed from a non-isolated system, some mass will be lost with it. High energy losses result in loss of weighable amounts of mass, an important topic in nuclear chemistry. * Law of definite composition, although in many systems (notably biomacromolecules and minerals) the ratios tend to require large numbers, and are frequently represented as a fraction. * Law of multiple proportions * Raoult's law History The history of chemistry spans a period from very old times to the present. Since several millennia BC, civilizations were using technologies that would eventually form the basis of the various branches of chemistry. Examples include extracting metals from ores, making pottery and glazes, fermenting beer and wine, extracting chemicals from plants for medicine and perfume, rendering fat into soap, making glass, and making alloys like bronze. Chemistry was preceded by its protoscience, alchemy, which is an intuitive but non-scientific approach to understanding the constituents of matter and their interactions. It was unsuccessful in explaining the nature of matter and its transformations, but, by performing experiments and recording the results, alchemists set the stage for modern chemistry. Chemistry as a body of knowledge distinct from alchemy began to emerge when a clear differentiation was made between them by Robert Boyle in his work The Sceptical Chymist (1661). While both alchemy and chemistry are concerned with matter and its transformations, the crucial difference was given by the scientific method that chemists employed in their work. Chemistry is considered to have become an established science with the work of Antoine Lavoisier, who developed a law of conservation of mass that demanded careful measurement and quantitative observations of chemical phenomena. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs.Selected Classic Papers from the History of Chemistry =Of definition= The definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term "chymistry", in the view of noted scientist Robert Boyle in 1661, meant the subject of the material principles of mixed bodies. In 1663, the chemist Christopher Glaser described "chymistry" as a scientific art, by which one learns to dissolve bodies, and draw from them the different substances on their composition, and how to unite them again, and exalt them to a higher perfection. as found in: The 1730 definition of the word "chemistry", as used by Georg Ernst Stahl, meant the art of resolving mixed, compound, or aggregate bodies into their principles; and of composing such bodies from those principles. In 1837, Jean-Baptiste Dumas considered the word "chemistry" to refer to the science concerned with the laws and effects of molecular forces.Dumas, J.B. (1837). 'Affinite' (lecture notes), vii, p 4. "Statique chimique", Paris: Académie des Sciences This definition further evolved until, in 1947, it came to mean the science of substances: their structure, their properties, and the reactions that change them into other substances – a characterization accepted by Linus Pauling. More recently, in 1998, Professor Raymond Chang broadened the definition of "chemistry" to mean the study of matter and the changes it undergoes. =Of discipline= Democritus' atomist philosophy was later adopted by Epicurus (341–270 BCE). Early civilizations, such as the EgyptiansFirst chemists, February 13, 1999, New Scientist Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didn't develop a systematic theory. A basic chemical hypothesis first emerged in Classical Greece with the theory of four elements as propounded definitively by Aristotle stating that fire, air, earth and water were the fundamental elements from which everything is formed as a combination. Greek atomism dates back to 440 BC, arising in works by philosophers such as Democritus and Epicurus. In 50 BCE, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura (On The Nature of Things). Unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. An early form of the idea of conservation of mass is the notion that "Nothing comes from nothing" in Ancient Greek philosophy, which can be found in Empedocles (approx. 4th century BC): "For it is impossible for anything to come to be from what is not, and it cannot be brought about or heard of that what is should be utterly destroyed."Fr. 12; see pp.291-2 of and Epicurus (3rd century BC), who, describing the nature of the Universe, wrote that "the totality of things was always such as it is now, and always will be". In the Hellenistic world the art of alchemy first proliferated, mingling magic and occultism into the study of natural substances with the ultimate goal of transmuting elements into gold and discovering the elixir of eternal life. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. Alchemy continued to be developed and practised throughout the Arab world after the Muslim conquests,Morris Kline (1985) Mathematics for the nonmathematician. Courier Dover Publications. p. 284. and from there, and from the Byzantine remnants,Marcelin Berthelot, Collection des anciens alchimistes grecs (3 vol., Paris, 1887–1888, p. 161); F. Sherwood Taylor, "The Origins of Greek Alchemy," Ambix 1 (1937), 40. diffused into medieval and Renaissance Europe through Latin translations. Jābir ibn Hayyān (Geber), a Perso-Arab alchemist whose experimental research laid the foundations of chemistry. The development of the modern scientific method was slow and arduous, but an early scientific method for chemistry began emerging among early Muslim chemists, beginning with the 9th century Perso-Arab chemist Jābir ibn Hayyān (known as "Geber" in Europe), who is sometimes referred to as "the father of chemistry". John Warren (2005). "War and the Cultural Heritage of Iraq: a sadly mismanaged affair", Third World Quarterly, Volume 26, Issue 4 & 5, pp. 815–830. Dr. A. Zahoor (1997), Jâbir ibn Hayyân (Geber)Paul Vallely, How Islamic inventors changed the world, The Independent, 10 March 2006 He introduced a systematic and experimental approach to scientific research based in the laboratory, in contrast to the ancient Greek and Egyptian alchemists whose works were largely allegorical and often unintelligible.Kraus, Paul, Jâbir ibn Hayyân, Contribution à l'histoire des idées scientifiques dans l'Islam. I. Le corpus des écrits jâbiriens. II. Jâbir et la science grecque,. Cairo (1942–1943). Repr. By Fuat Sezgin, (Natural Sciences in Islam. 67–68), Frankfurt. 2002: (cf. ) He also introduced the alembic (al-anbiq) of Persian encyclopedist Ibn al-Awwam to Europe, chemically analyzed many chemical substances, composed lapidaries, distinguished between alkalis and acids, and manufactured hundreds of drugs.Will Durant (1980). The Age of Faith (The Story of Civilization, Volume 4), p. 162-186. Simon & Schuster. . His books strongly influenced the medieval European alchemists and justified their search for the philosopher's stone. In the Middle Ages, Jabir's treatises on alchemy were translated into Latin and became standard texts for European alchemists. These include the Kitab al-Kimya (titled Book of the Composition of Alchemy in Europe), translated by Robert of Chester (1144); and the Kitab al-Sab'een (Book of Seventy) by Gerard of Cremona (before 1187). Later influential Muslim philosophers, such as Abū al-Rayhān al-Bīrūnī, AvicennaRobert Briffault (1938). The Making of Humanity, pp. 196–197. and Al-Kindi disputed the theories of alchemy, particularly the theory of the transmutation of metals. Under the influence of the new empirical methods propounded by Sir Francis Bacon and others, a group of chemists at Oxford, Robert Boyle, Robert Hooke and John Mayow began to reshape the old alchemical traditions into a scientific discipline. Boyle in particular is regarded as the founding father of chemistry due to his most important work, the classic chemistry text The Sceptical Chymist where the differentiation is made between the claims of alchemy and the empirical scientific discoveries of the new chemistry."Robert Boyle, Founder of Modern Chemistry" Harry Sootin (2011) He formulated Boyle's law, rejected the classical "four elements" and proposed a mechanistic alternative of atoms and chemical reactions that could be subject to rigorous experiment. Antoine-Laurent de Lavoisier is considered the "Father of Modern Chemistry". The theory of phlogiston (a substance at the root of all combustion) was propounded by the German Georg Ernst Stahl in the early 18th century and was only overturned by the end of the century by the French chemist Antoine Lavoisier, the chemical analogue of Newton in physics; who did more than any other to establish the new science on proper theoretical footing, by elucidating the principle of conservation of mass and developing a new system of chemical nomenclature used to this day. Before his work, though, many important discoveries had been made, specifically relating to the nature of 'air' which was discovered to be composed of many different gases. The Scottish chemist Joseph Black (the first experimental chemist) and the Dutchman J.B. van Helmont discovered carbon dioxide, or what Black called 'fixed air' in 1754; Henry Cavendish discovered hydrogen and elucidated its properties and Joseph Priestley and, independently, Carl Wilhelm Scheele isolated pure oxygen. English scientist John Dalton proposed the modern theory of atoms; that all substances are composed of indivisible 'atoms' of matter and that different atoms have varying atomic weights. The development of the electrochemical theory of chemical combinations occurred in the early 19th century as the result of the work of two scientists in particular, J.J. Berzelius and Humphry Davy, made possible by the prior invention of the voltaic pile by Alessandro Volta. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current. In his periodic table, Dmitri Mendeleev predicted the existence of 7 new elements, and placed all 60 elements known at the time in their correct places.Note: "...it is surely true that had Mendeleev never lived modern chemists would be using a Periodic Table" and British William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. J.A.R. Newlands devised an early table of elements, which was then developed into the modern periodic table of elements in the 1860s by Dmitri Mendeleev and independently by several other scientists including Julius Lothar Meyer."What makes these family likenesses among the elements? In the 1860s everyone was scratching their heads about that, and several scientists moved towards rather similar answers. The man who solved the problem most triumphantly was a young Russian called Dmitri Ivanovich Mendeleev, who visited the salt mine at Wieliczka in 1859." The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated charge. At the turn of the twentieth century the theoretical underpinnings of chemistry were finally understood due to a series of remarkable discoveries that succeeded in probing and discovering the very nature of the internal structure of atoms. In 1897, J.J. Thomson of Cambridge University discovered the electron and soon after the French scientist Becquerel as well as the couple Pierre and Marie Curie investigated the phenomenon of radioactivity. In a series of pioneering scattering experiments Ernest Rutherford at the University of Manchester discovered the internal structure of the atom and the existence of the proton, classified and explained the different types of radioactivity and successfully transmuted the first element by bombarding nitrogen with alpha particles. His work on atomic structure was improved on by his students, the Danish physicist Niels Bohr and Henry Moseley. The electronic theory of chemical bonds and molecular orbitals was developed by the American scientists Linus Pauling and Gilbert N. Lewis. The year 2011 was declared by the United Nations as the International Year of Chemistry. It was an initiative of the International Union of Pure and Applied Chemistry, and of the United Nations Educational, Scientific, and Cultural Organization and involves chemical societies, academics, and institutions worldwide and relied on individual initiatives to organize local and regional activities. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhler's synthesis of urea which proved that living organisms were, in theory, reducible to chemistry. Other crucial 19th century advances were; an understanding of valence bonding (Edward Frankland in 1852) and the application of thermodynamics to chemistry (J. W. Gibbs and Svante Arrhenius in the 1870s). Practice=Subdisciplines= Chemistry is typically divided into several major sub- disciplines. There are also several main cross-disciplinary and more specialized fields of chemistry. * Analytical chemistry is the analysis of material samples to gain an understanding of their chemical composition and structure. Analytical chemistry incorporates standardized experimental methods in chemistry. These methods may be used in all subdisciplines of chemistry, excluding purely theoretical chemistry. * Biochemistry is the study of the chemicals, chemical reactions and chemical interactions that take place in living organisms. Biochemistry and organic chemistry are closely related, as in medicinal chemistry or neurochemistry. Biochemistry is also associated with molecular biology and genetics. * Inorganic chemistry is the study of the properties and reactions of inorganic compounds. The distinction between organic and inorganic disciplines is not absolute and there is much overlap, most importantly in the sub-discipline of organometallic chemistry. * Materials chemistry is the preparation, characterization, and understanding of substances with a useful function. The field is a new breadth of study in graduate programs, and it integrates elements from all classical areas of chemistry with a focus on fundamental issues that are unique to materials. Primary systems of study include the chemistry of condensed phases (solids, liquids, polymers) and interfaces between different phases. * Neurochemistry is the study of neurochemicals; including transmitters, peptides, proteins, lipids, sugars, and nucleic acids; their interactions, and the roles they play in forming, maintaining, and modifying the nervous system. * Nuclear chemistry is the study of how subatomic particles come together and make nuclei. Modern Transmutation is a large component of nuclear chemistry, and the table of nuclides is an important result and tool for this field. * Organic chemistry is the study of the structure, properties, composition, mechanisms, and reactions of organic compounds. An organic compound is defined as any compound based on a carbon skeleton. * Physical chemistry is the study of the physical and fundamental basis of chemical systems and processes. In particular, the energetics and dynamics of such systems and processes are of interest to physical chemists. Important areas of study include chemical thermodynamics, chemical kinetics, electrochemistry, statistical mechanics, spectroscopy, and more recently, astrochemistry. Physical chemistry has large overlap with molecular physics. Physical chemistry involves the use of infinitesimal calculus in deriving equations. It is usually associated with quantum chemistry and theoretical chemistry. Physical chemistry is a distinct discipline from chemical physics, but again, there is very strong overlap. * Theoretical chemistry is the study of chemistry via fundamental theoretical reasoning (usually within mathematics or physics). In particular the application of quantum mechanics to chemistry is called quantum chemistry. Since the end of the Second World War, the development of computers has allowed a systematic development of computational chemistry, which is the art of developing and applying computer programs for solving chemical problems. Theoretical chemistry has large overlap with (theoretical and experimental) condensed matter physics and molecular physics. Other disciplines within chemistry are traditionally grouped by the type of matter being studied or the kind of study. These include inorganic chemistry, the study of inorganic matter; organic chemistry, the study of organic (carbon-based) matter; biochemistry, the study of substances found in biological organisms; physical chemistry, the study of chemical processes using physical concepts such as thermodynamics and quantum mechanics; and analytical chemistry, the analysis of material samples to gain an understanding of their chemical composition and structure. Many more specialized disciplines have emerged in recent years, e.g. neurochemistry the chemical study of the nervous system (see subdisciplines). Other fields include agrochemistry, astrochemistry (and cosmochemistry), atmospheric chemistry, chemical engineering, chemical biology, chemo-informatics, electrochemistry, environmental chemistry, femtochemistry, flavor chemistry, flow chemistry, geochemistry, green chemistry, histochemistry, history of chemistry, hydrogenation chemistry, immunochemistry, marine chemistry, materials science, mathematical chemistry, mechanochemistry, medicinal chemistry, molecular biology, molecular mechanics, nanotechnology, natural product chemistry, oenology, organometallic chemistry, petrochemistry, pharmacology, photochemistry, physical organic chemistry, phytochemistry, polymer chemistry, radiochemistry, solid-state chemistry, sonochemistry, supramolecular chemistry, surface chemistry, synthetic chemistry, thermochemistry, and many others. =Industry= The chemical industry represents an important economic activity worldwide. The global top 50 chemical producers in 2013 had sales of US$980.5 billion with a profit margin of 10.3%. =Professional societies= * American Chemical Society * American Society for Neurochemistry * Chemical Institute of Canada * Chemical Society of Peru * International Union of Pure and Applied Chemistry * Royal Australian Chemical Institute * Royal Netherlands Chemical Society * Royal Society of Chemistry * Society of Chemical Industry * World Association of Theoretical and Computational Chemists * List of chemistry societies See also * Comparison of software for molecular mechanics modeling * Glossary of chemistry terms * International Year of Chemistry * List of chemists * List of compounds * List of important publications in chemistry * List of unsolved problems in chemistry * Outline of chemistry * Periodic systems of small molecules * Philosophy of chemistry * Science tourism ReferencesBibliography Further reading ;Popular reading * Atkins, P.W. Galileo's Finger (Oxford University Press) * Atkins, P.W. Atkins' Molecules (Cambridge University Press) * Kean, Sam. The Disappearing Spoon – and other true tales from the Periodic Table (Black Swan) London, 2010 * Levi, Primo The Periodic Table (Penguin Books) [1975] translated from the Italian by Raymond Rosenthal (1984) * Stwertka, A. A Guide to the Elements (Oxford University Press) ;Introductory undergraduate text books * Atkins, P.W., Overton, T., Rourke, J., Weller, M. and Armstrong, F. Shriver and Atkins inorganic chemistry (4th edition) 2006 (Oxford University Press) * Chang, Raymond. Chemistry 6th ed. Boston: James M. Smith, 1998. . Voet and Voet Biochemistry (Wiley) ;Advanced undergraduate-level or graduate text books * Atkins, P.W. Physical Chemistry (Oxford University Press) * Atkins, P.W. et al. Molecular Quantum Mechanics (Oxford University Press) * McWeeny, R. Coulson's Valence (Oxford Science Publications) * Pauling, L. The Nature of the chemical bond (Cornell University Press) * Pauling, L., and Wilson, E.B. Introduction to Quantum Mechanics with Applications to Chemistry (Dover Publications) * Smart and Moore Solid State Chemistry: An Introduction (Chapman and Hall) * Stephenson, G. Mathematical Methods for Science Students (Longman) External links * General Chemistry principles, patterns and applications. "