Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds. 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.
In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. Examples include 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 (astrophysics), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).
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.
is an early protoscientific
discipline combining elements of chemistry
, and art
. Alchemy has been practiced in ancient Egypt
, and China
, in Classical Greece
, in the Islamic empire
, and then in Europe
up to the 19th century — in a complex network of schools and philosophical systems spanning at least 2500 years.
Western alchemy has always been closely connected with Hermeticism, a philosophical and spiritual system that traces its roots to Hermes Trismegistus, a syncretic Egyptian-Greek deity and legendary alchemist. These two disciplines influenced the birth of Rosicrucianism, an important esoteric movement of the 17th century. In the 19th century, as mainstream alchemy evolved into modern chemistry, its mystic and Hermetic aspects became the focus of a modern spiritual alchemy, where material manipulations are viewed as mere symbols of spiritual transformations.
The alchemists did not follow what is now known as the scientific method, and much of the "knowledge" they produced was later found to be banal, limited, wrong, or meaningless. Today, the discipline is of interest mainly to historians of science and philosophy, and for its mystic, esoteric, and artistic aspects. Nevertheless, alchemy was one of the main precursors of modern sciences, and we owe to the ancient alchemists the discovery of many substances and processes that are the mainstay of modern chemical and metallurgical industries.
History and Philosophy of Chemistry
Wikipedia:WikiProject Chemicals/Data is a collection of links and references that are useful for chemistry-related works. This includes free online chemical databases, publications, patents, computer programs, and various tools.
Science is Fun
University of Wisconsin–Madison Chemistry Professor Bassam Z. Shakhashiri, shares the fun of science.
A good place to figure out what equals what.
General Chemistry Online
Clear text and comprehensive coverage of general chemistry topics by Fred Senese, Dept. of Chemistry Frostburg State University
General Chemistry Demonstration at Purdue
Video clips (and descriptions) of lecture demonstrations.
Intota Chemistry Experts
A large online listing of real-world chemistry expert biographies provides examples of the many areas of expertise and careers in chemistry.
Chemistry Webercises Directory
A large listing of chemistry resources maintained by Steven Murov, Emeritus Chemistry Professor Modesto Junior College.
MathMol (Mathematics and Molecules) is a good starting point for those interested in the field of molecular modeling.
Educational Resources and Essential References from Wiley, the world's largest chemistry publisher
A directory of free full-text journals in chemistry, biochemistry and related subjects.
The Element Song
A goofy little song about all of the elements.
(1868-1934) was a German chemist, known as "the father of chemical warfare
" due to his work in developing and deploying chlorine
and other poisonous gases
for use in World War I. Along with Carl Bosch
, he developed the Haber process
, which is the catalytic
formation of ammonia
and atmospheric nitrogen
under conditions of relatively low temperature and high pressure. This is considered an important milestone in industrial chemistry, and he received the 1918 Nobel Prize in Chemistry
for this work. As part of his work in chemical warfare, he developed gas masks
with absorbent filters, and formulated a mathematical relationship between gas concentration and necessary exposure time to induce death, known as Haber's rule
. He is also associated with the development of the cyanide
formulation, Zyklon B
Techniques used by chemists
Equipment used by chemists
Chemistry in society
Chemistry in industry
Background color shows subcategory in the metal–metalloid–nonmetal trend:
Note: Nihonium, moscovium, tennessine, and oganesson have only recently been named.
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Collaboration of the Month
Every month a different chemistry-related topic, stub or non-existent article may be picked. Please improve the article any way you can.