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For other uses, see Chemistry (disambiguation).
Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.
Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Matter is commonly defined as being anything that has mass and that takes up space. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called
Chemistry is the study of interactions of chemical substances with one another and energy
Chemistry is the study of interactions of chemical substances with one another and energy

Chemistry (from Egyptian kēme (chem), meaning "earth"[1]) is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions. Egyptian is an Afro-Asiatic language most closely related to the Berber, Semitic, Somali and Beja languages Many ancient philosophies used a set of archetypal classical "elements" to explain patterns in Nature. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding Matter is commonly defined as being anything that has mass and that takes up space. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called [2] Historically, modern chemistry evolved out of alchemy following the chemical revolution (1773). Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of The Chemical Revolution, also called the first chemical revolution, denotes the reformulation of Chemistry based on the Law of Conservation of Matter and Chemistry is a physical science related to studies of various atoms, molecules, crystals and other aggregates of matter whether in isolation or combination, which incorporates the concepts of energy and entropy in relation to the spontaneity of chemical processes. Physical science is an encompassing term for the branches of Natural science and Science that study non-living systems in contrast to the biological sciences History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy A spontaneous process is the time-evolution of a system in which it releases free energy (most often as heat and moves to a lower more thermodynamically stable energy state In a " scientific " sense a chemical process is a method or means of somehow changing one or more Chemicals or Chemical compounds Such a chemical

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 matter; biochemistry, the study of substances found in biological organisms; physical chemistry, the energy related studies of chemical systems at macro, molecular and submolecular scales; analytical chemistry, the analysis of material samples to gain an understanding of their chemical composition and structure. Inorganic chemistry is the branch of Chemistry concerned with the properties and behavior of Inorganic compounds This field covers all Chemical compounds Traditionally inorganic compounds are considered to be of mineral not biological origin Organic chemistry is a discipline within Chemistry which involves the scientific study of the structure properties composition reactions, and preparation An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as A chemical substance is a Material with a definite chemical composition. Physical chemistry, is the application of Physics to macroscopic microscopic atomic subatomic and particulate phenomena in chemical systems It is mostly defined as a large In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Analytical chemistry is the study of the Chemical composition of natural and artificial Materials. Use in chemistry In Chemistry, the empirical formula of a Chemical compound is a simple expression of the relative number of each type of Atom Chemical structure refers to Molecular geometry, Electronic structure and Crystal structure. Many more specialized disciplines have emerged in recent years, e. g. neurochemistry the chemical study of the nervous system (see subdisciplines). Neurochemistry is the branch of Neuroscience devoted to the study of Neurochemicals A neurochemical is an organic molecule that participates in neural activity

Contents

Overview

Chemistry is the scientific study of interaction of chemical substances[3] that are constituted of atoms or the subatomic components that make up atoms: protons, electrons and neutrons. A chemical substance is a Material with a definite chemical composition. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. [4] Atoms combine to produce molecules or crystals. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Chemistry can be called "the central science" because it connects the other natural sciences, such as astronomy, physics, material science, biology, and geology. Chemistry is often called the central science because of its role in connecting “ Hard sciences such as Physics with the “ Soft sciences In Science, the term natural science refers to a naturalistic approach to the study of the Universe, which is understood as obeying rules or law of Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Materials Science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of Science and Foundations of modern biology There are five unifying principles Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit [5][6]

The genesis of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the middle east. Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of A millennium (pl millennia) is a period of Time equal to one thousand Years (from Latin la mille, thousand and la annum [7]

The structure of objects we commonly use and the properties of the matter we commonly interact with, are a consequence of the properties of chemical substances and their interactions. For example, steel is harder than iron because its atoms are bound together in a more rigid crystalline lattice; wood burns or undergoes rapid oxidation because it can react spontaneously with oxygen in a chemical reaction above a certain temperature; sugar and salt dissolve in water because their molecular/ionic properties are such that dissolution is preferred under the ambient conditions. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Hardness refers to various properties of Matter in the Solid phase that give it high resistance to various kinds of shape change when Force In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature

The transformations that are studied in chemistry are a result of interaction either between different chemical substances or between matter and energy. Matter is commonly defined as being anything that has mass and that takes up space. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Traditional chemistry involves study of interactions between substances in a chemistry laboratory using various forms of laboratory glassware. Interaction is a kind of action that occurs as two or more objects have an Effect upon one another A chemical substance is a Material with a definite chemical composition. A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially

Laboratory, Institute of Biochemistry, University of Cologne
Laboratory, Institute of Biochemistry, University of Cologne

A chemical reaction is a transformation of some substances into one or more other substances. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called [8] It can be symbolically depicted through a chemical equation. A chemical equation is a symbolic representation of a Chemical reaction. The number of atoms on the left and the right in the equation for a chemical transformation is most often equal. The nature 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. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy Chemical substances are classified in terms of their structure, phase as well as their chemical compositions. Structure is a fundamental and sometimes Intangible notion covering the Recognition, Observation, nature, and Stability of Use in chemistry In Chemistry, the empirical formula of a Chemical compound is a simple expression of the relative number of each type of Atom They can be analysed using the tools of chemical analysis, e. Analytical chemistry is the study of the Chemical composition of natural and artificial Materials. g. spectroscopy and chromatography. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ Chromatography (from Greek χρώμα chroma, color and γραφειν"graphein" to write is the collective term for a family of Laboratory

Chemistry is an integral part of the science curriculum both at the high school as well as the early college level. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding High school is the name used in some parts of the world (in particular Scotland, North America and Australia) to describe an institution At these levels, it is often called 'general chemistry' which is an introduction to a wide variety of fundamental concepts that enable the student to acquire tools and skills useful at the advanced levels, whereby chemistry is invariably studied in any of its various sub-disciplines. Scientists, engaged in chemical research are known as chemists. A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices Research is defined as Human activity based on Intellectual application in the investigation of Matter. A chemist is a Scientist trained in the Science of Chemistry. [9] Most chemists specialize in one or more sub-disciplines.

History

Main article: History of chemistry
See also: Alchemy, Timeline of chemistry, and Nobel Prize in Chemistry

The genesis of chemistry can be traced to the widely observed phenomenon of burning that led to metallurgy- the art and science of processing ores to get metals (e. The history of Chemistry begins with the discovery of Fire, then Metallurgy which allowed purification of metals and the making of alloys as well as the exploitation Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of Timeline of chemistry lists important works discoveries ideas inventions and experiments that significantly changed mankind's understanding of the composition of matter The Nobel Prize in Chemistry (Nobelpriset i kemi is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of Chemistry. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Metallurgy is a domain of Materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their g. metallurgy in ancient India). HyderAlijpg|thumb|200px|right| Hyder Ali (c 1722-1782—the ruler of the Kingdom of Mysore till 1782—developed military rockets using metal cylinders to contain the combustion The greed for gold led to the discovery of the process for its purification, even though, the underlying principles were not well understood -- it was thought to be a transformation rather than purification. Many scholars in those days thought it reasonable to believe that there exist means for transforming cheaper (base) metals into gold. This gave way to alchemy, and the search for the Philosopher's Stone, which was believed to bring about such a transformation by mere touch. The philosopher's stone (lapis philosophorum Greek: Chrysopoeia) is a Legendary substance supposedly capable of turning inexpensive Metals [10]

Some consider medieval Muslims to be the earliest chemists, who introduced precise observation and controlled experimentation into the field, and discovered numerous chemical substances. Observation is either an activity of a living being (such as a Human) which senses and assimilates the Knowledge of a Phenomenon, or the recording of data In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or A chemical substance is a Material with a definite chemical composition. [11] The most influential Muslim chemists were Geber (d. For the 12th century astronomer see Jabir ibn Aflah. For the anonymous 14th century Spanish alchemist see Pseudo-Geber. 815), al-Kindi (d. ( أبو يوسف يعقوب إبن إسحاق الكندي) (c 873), al-Razi (d. 925), and al-Biruni (d. 1048). [12] The works of Geber became more widely known in Europe through Latin translations by a pseudo-Geber in 14th century Spain, who also wrote some of his own books under the pen name "Geber". Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Pseudo-Geber ("false Geber " is the name assigned by modern scholars to an alchemist born in the 13th century, probably Paul of Taranto in Spain Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. The contribution of Indian alchemists and metallurgists in the development of chemistry was also quite significant. HyderAlijpg|thumb|200px|right| Hyder Ali (c 1722-1782—the ruler of the Kingdom of Mysore till 1782—developed military rockets using metal cylinders to contain the combustion [13]

The emergence of chemistry in Europe was primarily due to the recurrent incidence of the plague and blights there during the so called Dark Ages. Bubonic plague is the best-known manifestation of the bacterial disease plague, caused by the bacterium Yersinia pestis (formerly known as This article is about the phrase "Dark Age(s" as a characterization of the Early Middle Ages in Western Europe This gave rise to a need for medicines. It was thought that there exists a universal medicine called the Elixir of Life that can cure all diseases, but like the Philosopher's Stone, it was never found. The elixir of life, from Arabic الإكسير also known as the elixir of immortality or Dancing Water or Persian: Aab-e-Hayaat آب حیات

For some practitioners, alchemy was an intellectual pursuit, over time, they got better at it. Paracelsus (1493-1541), for example, rejected the 4-elemental theory and with only a vague understanding of his chemicals and medicines, formed a hybrid of alchemy and science in what was to be called iatrochemistry. Paracelsus (11 November or 17 December 1493 in Einsiedeln Switzerland – 24 September 1541 in Salzburg, Austria) was an alchemist, Iatrochemistry (or Chemiatry) is a branch of both Chemistry and Medicine. Similarly, the influences of philosophers such as Sir Francis Bacon (1561-1626) and René Descartes (1596-1650), who demanded more rigor in mathematics and in removing bias from scientific observations, led to a scientific revolution. Francis Bacon 1st Viscount St Alban KC QC (22 January 1561 – 9 April 1626 was an English Philosopher, Statesman, and author The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published In chemistry, this began with Robert Boyle (1627-1691), who came up with an equations known as the Boyle's Law about the characteristics of gaseous state. Robert Boyle was a Natural philosopher, chemist physicist inventor and early Gentleman scientist, noted for his work in Physics and Chemistry Boyle's law (sometimes referred to as the Boyle-Mariotte law) is one of several Gas laws and a special case of the Ideal gas law. [14] Chemistry indeed came of age when Antoine Lavoisier (1743-1794), developed the theory of Conservation of mass in 1783; and the development of the Atomic Theory by John Dalton around 1800. The law of conservation of mass/matter, also known as law of mass/matter conservation (or the Lomonosov - Lavoisier law says that the Mass of This article focuses on the historical models of the atom For a history of the study of how atoms combine to form molecules see History of the molecule. John Dalton FRS (6 September 1766 &ndash 27 July 1844 was an English Chemist, Meteorologist and Physicist. The Law of Conservation of Mass resulted in the reformulation of chemistry based on this law and the oxygen theory of combustion, which was largely based on the work of Lavoisier. Lavoisier's fundamental contributions to chemistry were a result of a conscious effort to fit all experiments into the framework of a single theory. He established the consistent use of the chemical balance, used oxygen to overthrow the phlogiston theory, and developed a new system of chemical nomenclature and made contribution to the modern metric system. The phlogiston theory (from the Ancient Greek φλογιστόν phlŏgistón "burning up" from φλόξ phlóx "fire" first stated Lavoisier also worked to translate the archaic and technical language of chemistry into something that could be easily understood by the largely uneducated masses, leading to an increased public interest in chemistry. All these advances in chemistry led to what is usually called the chemical revolution. The Chemical Revolution, also called the first chemical revolution, denotes the reformulation of Chemistry based on the Law of Conservation of Matter and The contributions of Lavoisier led to what is now called modern chemistry - the chemistry that is studied in educational institutions all over the world. It is because of these and other contributions that Antoine Lavoisier is often celebrated as the "Father of Modern Chemistry". The later discovery of Friedrich Wöhler that many natural substances, organic compounds, can indeed be synthesized in a chemistry laboratory also helped the modern chemistry to mature from its infancy. Friedrich Wöhler (31 July 1800 - 23 September 1882 was a German Chemist, best-known for his synthesis of Urea, but also the first to isolate several An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and

The discoveries of the chemical elements has a long history from the days of alchemy and culminating in the creation of the periodic table of the chemical elements by Dmitri Mendeleev (1834-1907)[15] and later discoveries of some synthetic elements. The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is Dmitri Ivanovich Mendeleev (sometimes spelled Mendeleyev; Дми́трий Ива́нович Менделе́ев) ( &ndash) was a Russian chemist and In chemistry the Chemical elements labeled as synthetic are too unstable to be found naturally on Earth.

Etymology

Main article: Chemistry (etymology)

The word chemistry comes from the earlier study of alchemy, which is basically the quest to make gold from earthen starting materials. In the History of science, the Etymology of the word Chemistry is a debatable issue [16] As to the origin of the word "alchemy" the question is a debatable one; it certainly can be traced back to the Greeks, and some, following E. Wallis Budge, have also asserted Egyptian origins. Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now Alchemy, generally, derives from the old French alkemie from the Arabic كيمياء al-kīmiyā' - "the art of transformation". The Arabs borrowed the word "kimia" from the Greeks when they conquered Alexandria in the year 642 AD. Alexandria ( Egyptian Arabic: اسكندريه Eskendereyya; Standard Arabic: ar الإسكندرية Al-Iskandariyya; Ἀλεξάνδρεια A tentative outline is as follows:

  1. Egyptian alchemy [3,000 BCE – 400 BCE], formulate early "element" theories such as the Ogdoad. In Egyptian mythology, the Ogdoad (Greek "οκτάδα" the number eight were eight deities worshipped in Hermopolis during what is called the Old
  2. Greek alchemy [332 BCE – 642 CE], the Greek king Alexander the Great conquers Egypt and founds Alexandria, having the world's largest library, where scholars and wise men gather to study. Alexander the Great ( or, Mégas Aléxandros; July 20 356 BC June 10 or June 11 323 BC also known as Alexander III of Macedon (el Ἀλέξανδρος Γ'
  3. Arabian alchemy [642 CE – 1200], the Arabs take over Alexandria; Jabir is the main chemist
  4. European alchemy [1300 – present], Pseudo-Geber builds on Arabic chemistry
  5. Chemistry [1661], Boyle writes his classic chemistry text The Sceptical Chymist
  6. Chemistry [1787], Lavoisier writes his classic Elements of Chemistry
  7. Chemistry [1803], Dalton publishes his Atomic Theory

Thus, 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". For the 12th century astronomer see Jabir ibn Aflah. For the anonymous 14th century Spanish alchemist see Pseudo-Geber. Pseudo-Geber ("false Geber " is the name assigned by modern scholars to an alchemist born in the 13th century, probably Paul of Taranto in Spain Robert Boyle was a Natural philosopher, chemist physicist inventor and early Gentleman scientist, noted for his work in Physics and Chemistry John Dalton FRS (6 September 1766 &ndash 27 July 1844 was an English Chemist, Meteorologist and Physicist.

Definitions

In retrospect, the definition of chemistry seems to invariably change per decade, as new discoveries and theories add to the functionality of the science. Shown below are some of the standard definitions used by various noted chemists:

Basic concepts

Several concepts are essential for the study of chemistry, some of them are:[24]

Atom

Main article: Atom

An atom is the basic unit of an element. The term "concept" is traced back to 1554–60 ( l conceptum - something conceived but what is today termed "the classical theory of concepts" is the theory of Aristotle History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny It is a collection of matter consisting of a positively charged core (the atomic nucleus) which contains protons and neutrons, and which maintains a number of electrons to balance the positive charge in the nucleus. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The atom is also the smallest entity that can be envisaged to retain some of 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. A chemical property is any of a material's properties that becomes evident during a Chemical reaction; that is any quality that can be established only by changing a substance's " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. The coordination number of an atom in a molecule or a crystal is the number of its nearest neighbours A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic g. , metallic, ionic, covalent). The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge

Element

Main article: Chemical element

The concept of chemical element is related to that of chemical substance. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. A chemical element is characterized by a particular number of protons in the nuclei of its atoms. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom This number is known as the atomic number of the element. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon, and all atoms with 92 protons in their nuclei are atoms of the element uranium. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the However, several isotopes of an element, that differ from one another in the number of neutrons present in the nucleus, may exist. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides

The most convenient presentation of the chemical elements is in the periodic table of the chemical elements, which groups elements by atomic number. The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is Due to its ingenious arrangement, groups, or columns, and periods, or rows, of elements in the table either share several chemical properties, or follow a certain trend in characteristics such as atomic radius, electronegativity, etc. In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In the Periodic table of the elements, a period is a horizontal row of the table Atomic radius, and more generally the size of an atom, is not a precisely defined Physical quantity, nor is it constant in all circumstances " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons Lists of the elements by name, by symbol, and by atomic number are also available. Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of chemical elements by symbol, including the A table of Chemical elements ordered by Atomic number and color coded according to type of element

Compound

Main article: Chemical compound

A compound is a substance with a particular ratio of atoms of particular chemical elements which determines its composition, and a particular organization which determines chemical properties. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Chemical structure refers to Molecular geometry, Electronic structure and Crystal structure. For example, water is a compound containing hydrogen and oxygen in the ratio of two to one, with the oxygen between the hydrogens, and an angle of 104. Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 5° between them. Compounds are formed and interconverted by chemical reactions. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called

Substance

Main article: Chemical substance

A chemical substance is a kind of matter with a definite composition and set of properties. A chemical substance is a Material with a definite chemical composition. Use in chemistry In Chemistry, the empirical formula of a Chemical compound is a simple expression of the relative number of each type of Atom A chemical property is any of a material's properties that becomes evident during a Chemical reaction; that is any quality that can be established only by changing a substance's Strictly speaking, a mixture of compounds, elements or compounds and elements is not a chemical substance, but it may be called a chemical. Most of the substances we encounter in our daily life are some kind of mixture, e. g. air, alloys, biomass etc. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Biomass refers to living and recently dead Biological material that can be used as fuel or for industrial production

Nomenclature of substances is a critical part of the language of chemistry. Generally it refers to a system for naming chemical compounds. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. Earlier in the history of chemistry substances were given name by their discoverer, which often led to some confusion and difficulty. However, today the IUPAC system of chemical nomenclature allows chemists to specify by name specific compounds amongst the infinite variety of possible chemicals. The standard nomenclature of chemical substances is set by the International Union of Pure and Applied Chemistry (IUPAC). The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization There are well-defined systems in place for naming chemical species. Organic compounds are named according to the organic nomenclature system. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied [25] Inorganic compounds are named according to the inorganic nomenclature system. Traditionally inorganic compounds are considered to be of mineral not biological origin The IUPAC nomenclature of inorganic chemistry is a systematic method of naming Inorganic Chemical compounds as recommended by the International Union [26] In addition the Chemical Abstracts Service has devised a method to index chemical substance. Chemical Abstracts Service ( CAS) is a division of the American Chemical Society, and produces Chemical Abstracts, and related products In this scheme each chemical substance is identifiable by a numeric number known as CAS registry number. CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to

Molecule

Main article: Molecule

A molecule is the smallest indivisible portion, beside an atom, 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. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by A chemical substance is a Material with a definite chemical composition. Molecules can exist as electrically neutral units unlike ions. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge 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. lone pair is a (valence electron pair without bonding or sharing with other Atoms They are found in the outermost Electron shell of an atom so lone pairs

A molecular structure depicts the bonds and relative positions of atoms in a molecule such as that in Paclitaxel shown here
A molecular structure depicts the bonds and relative positions of atoms in a molecule such as that in Paclitaxel shown here

One of the main characteristic of a molecule is its geometry often called its structure. Paclitaxel is a Mitotic inhibitor used in Cancer Chemotherapy. Molecular geometry or molecular structure is the three- Dimensional arrangement of the Atoms that constitute a Molecule. 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.

Mole

Main article: Mole (unit)

A mole is the amount of a substance that contains as many elementary entities (atoms, molecules or ions) as there are atoms in 0. The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this A chemical substance is a Material with a definite chemical composition. 012 kilogram (or 12 grams) of carbon-12, where the carbon-12 atoms are unbound, at rest and in their ground state. For other uses of the words gram or gramme see Gram (disambiguation. Carbon-12 is the most abundant of the two stable Isotopes of the element Carbon, accounting for 98 In Quantum mechanics, a stationary state is an Eigenstate of a Hamiltonian, or in other words a state of definite energy [27] This number is known as the Avogadro constant, and is determined empirically. The Avogadro constant (symbols L, N A also called Avogadro's number, is the number of "elementary entities" (usually Atoms The currently accepted value is 6. 02214179(30)×1023 mol-1 (2007 CODATA). CODATA ( Committee on Data for Science and Technology) was established in 1966 as an interdisciplinary committee of the International Council of Science (ICSU formerly It is much like the term "a dozen" in that it is an absolute number (having no units) and can describe any type of elementary object, although the mole's use is usually limited to measurement of subatomic, atomic, and molecular structures. Dozen is another word for the Number twelve. The dozen may be one of the earliest primitive groupings perhaps because there are approximately a dozen cycles of the A subatomic particle is an elementary or composite Particle smaller than an Atom. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by

The number of moles of a substance in one liter of a solution is known as its molarity. In Chemistry, a solution is a Homogeneous Mixture composed of two or more substances In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance Molarity is the common unit used to express the concentration of a solution in physical chemistry. In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance Physical chemistry, is the application of Physics to macroscopic microscopic atomic subatomic and particulate phenomena in chemical systems It is mostly defined as a large

Ions and salts

Main article: Ion

An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Positively charged cations (e. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge g. sodium cation Na+) and negatively charged anions (e. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge g. chloride Cl−) can form a crystalline lattice of neutral salts (e. The chloride Ion is formed when the element Chlorine picks up one Electron to form an Anion (negatively-charged ion Cl&minus Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants g. sodium chloride NaCl). For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Examples of polyatomic ions that do not split up during acid-base reactions are hydroxide (OH−) and phosphate (PO43−). A polyatomic ion is a charged species ( Ion) composed of two or more atoms covalently bonded or of a metal complex that can be considered as acting In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen A phosphate, an Inorganic chemical, is a salt of Phosphoric acid.

Ions in the gaseous phase is often known as plasma. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound

Phase

Main article: Phase (matter)

In addition to the specific chemical properties that distinguish different chemical classifications chemicals can exist in several phases. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties 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. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Physical properties, such as density and refractive index tend to fall within values characteristic of the phase. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium 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. In Thermodynamics, phase transition or phase change is the transformation of a thermodynamic system from one phase to another

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. A supercritical fluid is any substance at a Temperature and Pressure above its Thermodynamic critical point. 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. In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid

The most familiar examples of phases are solids, liquids, and gases. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of This page is about the physical properties of gas as a state of matter 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. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 A principal difference between solid phases is the crystal structure, or arrangement, of the atoms. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. Less familiar phases include plasmas, Bose-Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound A Bose–Einstein condensate (BEC is a State of matter of Bosons confined in an external Potential and cooled to Temperatures very near to A fermionic condensate is a Superfluid phase formed by Fermionic particles at low Temperatures It is closely related to the Bose-Einstein Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field Ferromagnetism is the basic mechanism by which certain materials (such as Iron) form Permanent magnets and/or exhibit strong interactions with Magnets it A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field. 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. Foundations of modern biology There are five unifying principles

Chemical bond

Main article: Chemical bond
Electron atomic and molecular orbitals
Electron atomic and molecular orbitals

A chemical bond is a concept for understanding how atoms stick together in molecules. A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Chemistry, a molecular orbital (or MO) is a region in which an Electron may be found in a Molecule. It may be visualized as the multipole balance between the positive charges in the nuclei and the negative charges oscillating about them. Multipole moments are the Coefficients of a Series expansion of a Potential due to continuous or discrete sources (e [28] More than simple attraction and repulsion, the energies and distributions characterize the availability of an electron to bond to another atom. These potentials create the interactions which holds together atoms in molecules or crystals. Interaction is a kind of action that occurs as two or more objects have an Effect upon one another History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating 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 predict molecular structure and composition. In Chemistry, valence bond theory explains the nature of a Chemical bond in a Molecule in terms of atomic valencies. Valence shell electron pair repulsion (VSEPR theory (1957 is a model in Chemistry, which is used for predicting the shapes of individual Molecules based The oxidation number of a central atom in a coordination compound is the charge that it would have if all the Ligands were removed along with the Electron pairs Similarly, theories from classical physics can be used to predict many ionic structures. With more complicated compounds, such as metal complexes, valence bond theory fails and alternative approaches, primarily based on principles of quantum chemistry such as the molecular orbital theory, are necessary. The term complex in Chemistry is usually used to describe molecules or ensembles formed by the combination of Ligands and metal Ions. Quantum chemistry is a branch of Theoretical chemistry, which applies Quantum mechanics and Quantum field theory to address issues and problems in In Chemistry, a molecular orbital (or MO) is a region in which an Electron may be found in a Molecule. See diagram on electronic orbitals.

Chemical reaction

Main article: Chemical reaction

Chemical reaction is a concept related to the transformation of a chemical substance through its interaction with another, or as a result of its interaction with some form of energy. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called A chemical substance is a Material with a definite chemical composition. In the context of Physical sciences several forms of Energy have been defined A chemical reaction may occur naturally or carried out in a laboratory by chemists in specially designed vessels which are often laboratory glassware. Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially It can result in the formation or dissociation of molecules, that is, molecules breaking apart to form two or more smaller molecules, or rearrangement of atoms within or across molecules. Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Chemical reactions usually involve the making or breaking of chemical bonds. A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic Oxidation, reduction, dissociation, acid-base neutralization and molecular rearrangement are some of the commonly used kinds of chemical reactions. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate A rearrangement reaction is a broad class of Organic reactions where the carbon skeleton of a Molecule is rearranged to give a Structural isomer of the original

A chemical reaction can be symbolically depicted through a chemical equation. A chemical equation is a symbolic representation of a Chemical reaction. 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. [29]

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. Chemistry, a reaction mechanism is the step by step Sequence of Elementary reactions by which overall Chemical change occurs. 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. A reaction intermediate or an intermediate is a Molecular entity that is formed from the reactants (or preceding intermediates and reacts further to give the directly Reaction mechanisms are proposed to explain the kinetics and the relative product mix of a reaction. Chemical kinetics, also known as reaction kinetics is the study of rates of chemical processes Many physical chemists specialize in exploring and proposing the mechanisms of various chemical reactions. A chemist is a Scientist trained in the Science of Chemistry. Several empirical rules, like the Woodward-Hoffmann rules often come handy while proposing a mechanism for a chemical reaction.

A stricter definition is that "a chemical reaction is a process that results in the interconversion of chemical species". [30] Under this definition, a chemical reaction may be an elementary reaction or a stepwise reaction. An elementary reaction is a Chemical reaction in which one or more of the Chemical species which react directly to form products in a single Reaction step A stepwise reaction is a Chemical reaction with one or more Reaction intermediates and involving at least two consecutive Elementary reactions The rate An additional caveat is made, in that this definition includes cases where the interconversion of conformers is experimentally observable. In Chemistry, conformational isomerism is a form of Stereoisomerism in which Molecules with the same Structural formula (same connectivity 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').

Energy

Main article: Energy

All chemical substances have energy as a consequence of their atomic, or molecular or aggregrate structure. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny Molecular geometry or molecular structure is the three- Dimensional arrangement of the Atoms that constitute a Molecule. Since a chemical transformation e. g. a chemical reaction is accompanied by a change in structure of the molecules or aggregrates involved, it is invariably accompanied by an increase or decrease of energy of the substances involved. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat. An exothermic reaction is a Chemical reaction that releases Heat. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός 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. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Photochemistry, a sub-discipline of Chemistry, is the study of the interactions between Atoms, small Molecules, and light (or Electromagnetic radiation A reaction is said to be exothermic if the final state is lower on the energy scale than the initial state; in case of endothermic reactions the situation is otherwise. In Thermodynamics, the word exothermic "outside heating" describes a process or reaction that releases Energy usually in the form of Heat, but In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat.

Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. In Chemistry, activation energy, also called midnight energy, is a term introduced in 1889 by the Swedish scientist Svante Arrhenius, that is defined 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 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 Arrhenius equation is a simple but remarkably accurate formula for the temperature dependence of the Rate constant, and therefore rate of a chemical reaction The activation energy necessary for a chemical reaction can be in the form of heat, light, electricity or mechanical force in the form of ultrasound. In Physics, a force is whatever can cause an object with Mass to Accelerate. Not to be confused with Supersonic. Ultrasound is cyclic Sound pressure with a Frequency greater than the upper [31]

A related concept free energy, which incorporates entropy considerations too, 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. In Thermodynamics, the term thermodynamic free energy refers to the amount of work that can be extracted from a System, and is helpful in Engineering In Thermodynamics, chemical thermodynamics is the mathematical study of the interrelation of Heat and work with Chemical reactions or with a 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. In Thermodynamics, the Gibbs free energy ( IUPAC recommended name Gibbs energy or Gibbs function) is a Thermodynamic potential which In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change

There are only a 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. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons In Physics, quantization is a procedure for constructing a Quantum field theory starting from a classical field theory. The atoms/molecules in an 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 amenable to chemical reactions.

The phase of a substance is invariably determined by its energy and those of its surroundings. When the intermolecular forces of a substance are such that 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. A hydrogen bond results from a Dipole-dipole force between an Electronegative atom and a Hydrogen atom bonded to Nitrogen, Oxygen [32] Whereas hydrogen sulfide (H2S) is a gas at room temperature and standard pressure, as its molecules are bound by weaker dipole-dipole interactions. Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. In Physics, Chemistry, and Biology, intermolecular forces are forces that act between stable Molecules or between functional groups of

The transfer of energy from one chemical substance to other depend on the size of energy quanta emitted from one substance. However, heat energy is easily transferred from almost any substance to another mainly because the vibrational and rotational energy levels in a substance are very closely placed. Because, the electronic energy levels are not so closely spaced, ultraviolet electromagnetic radiation is not transferred with equal felicity, as is also the case with electrical energy.

The existence of characteristic energy levels for different chemical substances is useful for their identification by the analysis of spectral lines of different kinds of spectra often used in chemical spectroscopy e. A chemical substance is a Material with a definite chemical composition. A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range compared g. IR, microwave, NMR, ESR etc. Infrared spectroscopy (IR spectroscopy is the subset of Spectroscopy that deals with the Infrared region of the Electromagnetic spectrum. Rotational spectroscopy or microwave spectroscopy studies the absorption and emission Electromagnetic radiation (typically in the Microwave Electron paramagnetic resonance (EPR or electron spin resonance (ESR Spectroscopy is a technique for studying Chemical species that have one or more unpaired This is used to identify the composition of remote objects - like stars and far galaxies - by analyzing their radiation (see spectroscopy). Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ

Emission spectrum of iron
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 transform other chemical substances. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called

Chemical laws

Main article: Chemical law

Chemical reactions are governed by certain laws, which have become fundamental concepts in chemistry. Chemical laws are those Laws of nature relevant to Chemistry. Some of them are:

Subdisciplines

Chemistry is typically divided into several major sub-disciplines. In Chemistry, the law of multiple proportions is one of the basic laws and a major tool of chemical measurement ( Stoichiometry) Hess's law is a law of Physical chemistry named for Germain Hess 's expansion of the Hess Cycle and used to predict the enthalpy change and conservation of energy (denoted In Fick's laws of diffusion describe Diffusion and can be used to solve for the diffusion coefficient D. Established by François-Marie Raoult, Raoult's law states the Vapor pressure of an Ideal solution is dependent on the vapor pressure of each Henry's Law may sometimes refer to Lenz's Law In Chemistry, Henry's law is one of the Gas laws, formulated by William Henry. Boyle's law (sometimes referred to as the Boyle-Mariotte law) is one of several Gas laws and a special case of the Ideal gas law. In Thermodynamics and Physical chemistry, Charles's law is a gas law and specific instance of the Ideal gas law, which states that The expression Gay-Lussac's law is used for each of the two relationships named after the French chemist Joseph Louis Gay-Lussac and which concern the properties of Gases Avogadro's law ( Avogadro's Hypothesis, or Avogadro's Principle) is a Gas law named after Amedeo Avogadro, who in 1811 hypothesized There are also several main cross-disciplinary and more specialized fields of chemistry. [33]

Other fields include Astrochemistry, Atmospheric chemistry, Chemical Engineering, Chemical biology, Chemo-informatics, Electrochemistry, Environmental chemistry, Flavor chemistry, Flow chemistry, Geochemistry, Green chemistry, Histochemistry, History of chemistry, Hydrogenation chemistry, Materials science, Mathematical chemistry, Medicinal chemistry, Molecular Biology, Nanotechnology, Natural Product chemistry, Oenology, Organometallic chemistry, Petrochemistry, Pharmacology, Photochemistry, Phytochemistry, Polymer chemistry, Solid-state chemistry, Sonochemistry, Supramolecular chemistry, Surface chemistry, Synthetic Chemistry, Immunochemistry and Thermochemistry. Astrochemistry is the study of the Chemical elements found in outer space generally on larger scales than the Solar System, particularly in molecular gas clouds Atmospheric chemistry is a branch of Atmospheric science in which the Chemistry of the Earth's atmosphere and that of other planets is studied Chemical engineering is the branch of Engineering that deals with the application of Physical science (e Chemical biology is a scientific discipline spanning the fields of Chemistry and Biology that involves the application of chemical techniques and tools often compounds Cheminformatics (also known as chemoinformatics and chemical informatics) is the use of computer and informational techniques applied to a range of problems Electrochemistry is a branch of Chemistry that studies Chemical reactions which take place in a Solution at the interface of an electron conductor Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places In flow chemistry, a Chemical reaction is run in a continuously flowing stream rather than in Batch production. The field of geochemistry involves study of the chemical composition of the Earth and other Planets chemical processes and reactions that govern the composition Green chemistry, also called sustainable chemistry is a chemical philosophy encouraging the design of products and processes that reduce or eliminate the use and generation of hazardous Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and The history of Chemistry begins with the discovery of Fire, then Metallurgy which allowed purification of metals and the making of alloys as well as the exploitation Materials Science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of Science and Mathematical chemistry is the area of research engaged in the novel and nontrivial applications of mathematics to chemistry it concerns itself principally with the Mathematical modeling Molecular biology is the study of Biology at a molecular level Nanotechnology, sometimes shortened to nanotech, refers to a field of Applied science whose theme is the control of matter on an Atomic and Molecular Oenology ( BrE) or enology ( AmE) is the science and study of all aspects of Wine and Winemaking from the grape harvest to bottle Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal. Petrochemistry is the branch of Chemistry that studies the transformation of Crude oil ( Petroleum) and Natural gas into useful products and raw Pharmacology (from Greek grc φάρμακον pharmakon, "drug" and grc -λογία -logia) is the study of how Drugs Photochemistry, a sub-discipline of Chemistry, is the study of the interactions between Atoms, small Molecules, and light (or Electromagnetic radiation Phytochemistry is in the strict sense of the word the study of Phytochemicals These are chemicals derived from Plants In a narrower sense the terms are often used Polymer chemistry or macromolecular chemistry is a multidisciplinary Science that deals with the Chemical synthesis and chemical properties of Solid-state chemistry is the study of the synthesis structure and physical properties of solid materials In Chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems Supramolecular chemistry refers to the area of Chemistry that focuses on the Noncovalent bonding interactions of molecules Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including Solid - Liquid Immunochemistry is a branch of Chemistry that involves the study of the reactions and components on the Immune system. In Thermodynamics and Physical chemistry, thermochemistry is the study of the Heat evolved or absorbed in Chemical reactions Thermochemistry

Chemical industry

Main article: Chemical industry

The chemical industry represents an important economic activity. The chemical industry comprises the companies that produce industrial chemicals The chemical industry comprises the companies that produce industrial chemicals The global top 50 chemical producers in 2004 had sales of 587 billion US dollars with a profit margin of 8. The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been 1% and research and development spending of 2. The phrase research and development (also R and D or more often R&D) according to the Organization for Economic Co-operation and Development, refers 1% of total chemical sales. [34]

References

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  2. ^ Chemistry. (n. d. ). Merriam-Webster's Medical Dictionary. Retrieved August 19, 2007. Events 43 BC - Octavian, later known as Augustus compels the Roman Senate to elect him Consul. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
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  4. ^ Matter: Atoms from Democritus to Dalton by Anthony Carpi, Ph. D.
  5. ^ Theodore L. Brown, H. Eugene Lemay, Bruce Edward Bursten, H. Lemay. Chemistry: The Central Science. Prentice Hall; 8 edition (1999). ISBN 0130103101. Pages 3-4.
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    "Chemistry as a science was almost created by the Muslims; for in this field, where the Greeks (so far as we know) were confined to industrial experience and vague hypothesis, the Saracens introduced precise observation, controlled experiment, and careful records. A hypothesis (from Greek) consists either of a suggested explanation for a phenomenon (an event that is observable or of a reasoned proposal suggesting a possible Saracen was a term used by Europeans in the Middle Ages for Fatimids at first then later for all who professed the religion of Islam. Observation is either an activity of a living being (such as a Human) which senses and assimilates the Knowledge of a Phenomenon, or the recording of data In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or They invented and named the alembic (al-anbiq), chemically analyzed innumerable substances, composed lapidaries, distinguished alkalis and acids, investigated their affinities, studied and manufactured hundreds of drugs. An alembic (from Arabic Al-inbiq الأنبيق is an alchemical Still consisting of two Retorts connected by a tube A chemical substance is a Material with a definite chemical composition. A lapidary (the word means "concerned with stones" is an Artisan who practices the craft of working forming and finishing stone, Mineral, In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are A drug, broadly speaking is any chemical substance that when absorbed into the body Alchemy, which the Muslims inherited from Egypt, contributed to chemistry by a thousand incidental discoveries, and by its method, which was the most scientific of all medieval operations. "

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Further reading

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For a full list of external links and suppliers see Wikipedia:Chemical sources. The American Chemical Society ( ACS) is a Learned society ( Professional association) based in the United States that supports scientific inquiry The Chemical Institute of Canada is a Canadian professional umbrella organization for Chemists (Canadian Society for Chemistry chemical engineers (Canadian Chemical Society of Peru is a non-profit scientific institution devoted to Chemistry. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization The Royal Australian Chemical Institute Inc (The RACI is both the qualifying body in Australia for professional chemists and a Learned society promoting the science The Royal Society of Chemistry (RSC is a Learned society ( Professional association) in the United Kingdom with the goal of "advancing the The Society of Chemical Industry (SCI is a Learned society set up in 1881 'to further the application of Chemistry and related sciences for the public The World Association of Theoretical and Computational Chemists ( WATOC) is a scholarly association founded in 1982 "in order to encourage the development and application Table of Common Chemical Ingredients and Where to Find Them This page aims to list articles related to Chemistry. This is so that those interested in the subject can monitor changes to the pages by clicking on Related Changes in the sidebar and This is a list of famous chemists: (alphabetical order A Emil Abderhalden, (1877&ndash1950 Swiss chemist Richard Abegg The original list from this page has been split into the following three lists as the number of compounds became too long Some criteria for editing this page have been debated and are displayed The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is Timeline of chemistry lists important works discoveries ideas inventions and experiments that significantly changed mankind's understanding of the composition of matter Unsolved problems in chemistry tend to be questions of the kind "Can we make X chemical compound?" "Can we analyse it ?" "Can we purify it ?" A mind map is a Diagram used to represent Words, Ideas tasks or other items linked to and arranged radially around a central key word or idea

Dictionary

chemistry

-noun

  1. (uncountable) The branch of natural science that deals with the composition and constitution of substances and the changes that they undergo as a consequence of alterations in the constitution of their molecules.
  2. (countable) An application of chemical theory and method to a particular substance.
  3. (informal) The mutual attraction between two people; rapport.
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