History of chemistry

Portrait of Monsieur Lavoisier and his Wife, by Jacques-Louis David

The history of chemistry may be said to begin with the distinction of chemistry from alchemy by Robert Boyle in his work The Sceptical Chymist ( 1661). Both alchemy and chemistry are concerned with the nature of matter and its transformations but, in contrast with alchemists, chemists apply the scientific method defined in particular by Francis Bacon.

Early developments

Origins

Although the chemistry comes from the ancient Babylon, Egypt and especially Persia after Islam but, the birth of chemistry is often more strictly dated to Antoine Lavoisier's discovery of the law of conservation of mass, and thereby to his refutation of the phlogiston theory of combustion in 1783. (Phlogiston was supposed to be an almost undetectable substance liberated by flammable materials in burning.) Mikhail Lomonosov independently established a tradition of chemistry in Russia in the 18th century. Lomonosov also rejected the phlogiston theory, and anticipated the kinetic theory of gases. He regarded heat as a form of motion, and stated the idea of conservation of matter.

The vitalism debate and organic chemistry

History of science

Overview

Historiography of science

Theories and sociology of the history of science

Pre-experimental science

Science in early cultures

History of Medieval science

Scientific revolution

Natural sciences

Astronomy | Biology | Chemistry | Earth sciences | Physics

Social sciences

Interdisciplinary

History of pseudoscience

Scientific Timelines

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After the nature of combustion (see oxygen) was settled, another dispute, about vitalism and the essential distinction between organic and inorganic substances, was revolutionized by Friedrich Wöhler's (accidental) synthesis of urea from inorganic substances in 1828. Never before had an organic compound been synthesized from inorganic material. This opened a new research field in chemistry, and by the end of the 19th century, scientists were able to synthesize hundreds of organic compounds. The most important among them are mauve, magenta, and other synthetic dyes, as well as the widely used drug aspirin. The discovery also contributed greatly to the theory of isomerism.

The dispute about atomism

Throughout the 19th century, chemistry was divided between those who followed the atomic theory of John Dalton and those who did not, such as Wilhelm Ostwald and Ernst Mach. Although such proponents of the atomic theory as Amedeo Avogadro and Ludwig Boltzmann made great advances in explaining the behaviour of gases, this dispute was not finally settled until Jean Perrin's experimental investigation of Einstein's atomic explanation of Brownian motion in the first decade of the 20th century.

Well before the dispute had been settled, many had already applied the concept of atomism to chemistry. A major example was the ion theory of Svante Arrhenius which held that chemical reactions in solutions were reactions between ions.

The periodic table

For many decades, the list of known chemical elements had been steadily increasing. A great breakthrough in making sense of this long list (as well as, eventually, in understanding the internal structure of atoms as discussed above) was Dmitri Mendeleev and Lothar Meyer's development of the periodic table, and, particularly, Mendeleev's use of it to predict the existence and the properties of germanium, gallium, and scandium, which Mendeleev called ekasilicon, ekaaluminium, and ekaboron respectively. Mendeleev made his prediction in 1870; gallium was discovered in 1875, and was found to have roughly the same properties that Mendeleev predicted for it.

Industrial exploitation

The later part of the nineteenth century saw the exploitation of petrochemicals extracted from the earth. This provided oil for heat lighting & industrial applications and replaced the use of whale oil in previous centuries. Systematic production of refined materials provided a ready supply of products which not only provided energy, but also synthetic materials for clothing, medicine, and everyday disposable resources, by the twentieth century. These included plastics and chemicals used in fertilizers and detergents.

The modern definition of chemistry

Classically, before the 20th century, chemistry was defined as the science of the nature of matter and its transformations. It was therefore clearly distinct from physics who was not concerned with such dramatic transformation of matter. Moreover, in contrast to physics, chemistry was not using much of mathematics. Even some were particularly reluctant to using mathematics within chemistry. For example, Auguste Comte wrote in 1830:

Every attempt to employ mathematical methods in the study of chemical questions must be considered profoundly irrational and contrary to the spirit of chemistry.... if mathematical analysis should ever hold a prominent place in chemistry -- an aberration which is happily almost impossible -- it would occasion a rapid and widespread degeneration of that science.

However, in the second part of the 19th century, the situation changed and August Kekule wrote in 1867:

I rather expect that we shall someday find a mathematico-mechanical explanation for what we now call atoms which will render an account of their properties.

After the discovery by Ernest Rutherford and Niels Bohr of the atomic structure in 1912, and by Marie and Pierre Curie of the radioactivity, scientists had to change drastically their viewpoint on the nature of matter. The experience acquired by chemists was no longer pertinent to the study of the whole nature of matter but only to aspects related to the electron cloud surrounding the atomic nuclei and the movement of the latter in the electric field induced by the former (see Born-Oppenheimer approximation). The range of chemistry was thus restricted to the nature of matter around us in conditions which are not too far from standard conditions for temperature and pressure and in cases where the exposure to radiations is not too different from the natural microwave, visible or UV radiations on Earth. Chemistry was therefore re-defined as the science of matter that deals with the composition, structure, and properties of substances and with the transformations that they undergo. However the meaning of matter used here relates explicitly to substances made of atoms and molecules, disregarding the matter within the atomic nuclei and its nuclear reaction or matter within highly ionized plasmas. Nevertheless the field of chemistry is still, on our human scale, very broad and the claim that chemistry is everywhere is really not that inaccurate.

Quantum chemistry

Main article: Quantum chemistry

Some view the birth of quantum chemistry in the discovery of the Schrödinger equation and its application to hydrogen atom in 1926. However, the 1927 article of Walter Heitler and Fritz London is often recognised as the first milestone in the history of quantum chemistry. This is the first application of quantum mechanics to the diatomic hydrogen molecule. In the following years many progresses were performed by Robert S. Mulliken, Max Born, J. Robert Oppenheimer, Linus Pauling, Erich Hückel, Douglas Hartree, Vladimir Aleksandrovich Fock, to cite a few.

Still, skepticism remained as to the general power of quantum mechanics applied to complex chemical systems. The situation around 1930 is described by Paul Dirac:

The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.

Hence the quantum mechanical methods developed in the 1930s and 1940s are often referred to as theoretical molecular or atomic physics to underline the fact that they were more the application of quantum mechanics to chemistry and spectroscopy than answers to chemically relevant questions.

In the 1940s many physicists turned from molecular or atomic physics to nuclear physics (like J. Robert Oppenheimer or Edward Teller). In 1951, a milestone article in quantum chemistry is the seminal paper of Clemens C. J. Roothaan on Roothaan equations. It opened the avenue to the solution of the self-consistent field equations for small molecules like hydrogen or nitrogen. Those computations were performed with the help of tables of integrals which were computed on the most advanced computers of the time.

Molecular biology and biochemistry

By the mid 20th century, in principle, the integration of physics and chemistry was complete, with chemical properties explained as the result of the electronic structure of the atom; Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more complicated molecules. However, though some principles deduced from quantum mechanics were able to predict qualitatively some chemical features for biologically relevant molecules, they were, till the end of the 20th century, more a collection of rules and recipes than rigorous ab initio quantitative methods. This kind of approach culminated in the physical modelling of the DNA molecule, in essence, "the secret of life", in the words of Francis Crick. His partner in the discovery of the structure of DNA, James Watson, was to treasure a gift from Crick, a copy of Pauling's book. Watson and Crick deduced the structure of DNA by physical modelling in the 1950s. Their helical structure was simultaneously confirmed by Rosalind Franklin's x-ray crystallography at William Bragg's laboratory in Cambridge. Pauling was very close to discovery as well; however his hypothetical structure was a triple helix rather than the double helix of DNA. In the same year, the Miller-Urey experiment demonstrated that basic constituents of protein, simple amino acids, could themselves be built up from simpler molecules in a simulation of primordial processes on Earth.

Semiconductor processing

In the mid-twentieth century, control of the electronic structure of semiconductor materials was made precise by the creation of single-crystal circuits. Advances in processing technology, like that utilized in other parts of the materials industry, coupled with the advance of optical and x-ray sources, made possible the miniaturization of electrical circuits, culminating in the integrated circuits of the twentieth century. In this way computer program logic could be realized and mechanized for computation and control.