Chemistry

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.[2] Chemistry is a physical science related to studies of various atoms, molecules, crystals and other aggregrates of matter whether in isolation or combination. It also incorporates energy and entropy related studies to various chemical substances.
There are several specialized disciplines within chemistry, traditionally grouped by the type of matter being studied or the kind of study, the main amongst them are:
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.
Many more specialized disciplines have emerged (see Subdisciplines and applied fields).
Modern chemistry evolved out of alchemy following the chemical revolution (1773), through the reforms of many individuals, particularly French chemist Antoine Lavoisier who, among others, is considered the "father of modern chemistry". Other pioneers (fathers) of modern chemistry include: Robert Boyle (1661), John Dalton (1808),and Jöns Jakob Berzelius (1828), while some consider Geber (d. 815) to be the first chemist.[3][4][5]

Chemistry is the scientific study of interaction of substances called chemical substances[6] that are constituted of atoms or the subatomic components that make up atoms: protons, electrons and neutrons.[7] Atoms combine to produce ions, molecules or crystals. Chemistry can be called "the central science" because it connects the other natural sciences, such as astronomy, physics, material science, biology, and geology.[8][9]
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.[10]
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.
The transformations that are studied in chemistry are a result of interaction either between different chemical substances or between matter and energy. Traditional chemistry involves study of interactions between substances in a chemistry laboratory using various forms of laboratory glassware

A chemical reaction is a transformation of some such substances into one or more other such substances.[11] It can be symbolically depicted through a chemical equation. 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. Chemical substances are classified in terms of their structure, phase as well as their chemical compositions. They can be analysed using the tools of chemical analysis, e.g. spectroscopy and chromatography.
Chemistry is an integral part of the science curriculum both at the high school as well as the early college level. 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.[12] Most chemists specialize in one or more sub-disciplines.


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.g. metallurgy in ancient India). 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.[13]
Some consider medieval Muslims to be the earliest chemists, who introduced precise observation and controlled experimentation into the field, and discovered numerous chemical substances.[14] The most influential Muslim chemists were Geber (d. 815), al-Kindi (d. 873), al-Razi (d. 925), and al-Biruni (d. 1048).[15] 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". The contribution of Indian alchemists and metallurgists in the development of chemistry was also quite significant.[16]
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. 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.
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. 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. In chemistry, this began with Robert Boyle (1627-1691), who discovered gases, and came up with equations that were known as Boyle's Law.[17] 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 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 contibution to the modern metric system. 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 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 contribtuions that Antoine Lavoisier is often celebrated as the "Father of Modern Chemistry". The later discovery of Friedrich Wöhler that many natural substances, the organic compounds, can indeed be synthesized in a chemistry laboratory also helped the modern chemistry to mature from its infancy.
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)[18] and later discoveries of some synthetic elements.
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