History of chemistry

History of chemistry

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History of chemistry

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 of many minerals and natural substances.

The protoscience of alchemy attempted to explain the nature of matter and its transformations. This was followed by the development of a scientific method by Geber, and then refutations of alchemy and the classical elements by several Arabic chemists. Modern chemistry begins to emerge when a clear distinction is made between chemistry and alchemy by Robert Boyle in his work The Sceptical Chymist (1661). Chemistry then becomes a full-fledged science when Antoine Lavoisier develops his law of conservation of mass, which demands careful measurements and quantitative observations of chemical phenomena. So, while both alchemy and chemistry are concerned with the nature of matter and its transformations, it is only the chemists who apply the scientific method.The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs.

From fire to atomism

Arguably the first chemical reaction that was used in a controlled manner by mankind was fire. However, for millennia, in absence of a scientific understanding, fire was simply a mystical force that could transform one substance into another (burn the wood, or boil the water) while producing heat and light. Fire affected many aspects of early societies, ranging from the most simple facets of everyday life, such as cooking and habitat lighting, to more advanced technologies, such as pottery, bricks, and smelting of metals to make tools.

Philosophical attempts to rationalize why different substances have different properties (color, density, smell), exist in different states (gaseous, liquid, and solid), and react in a different manner when exposed to environments, for example to water or fire or temperature changes, led ancient philosophers to postulate the first theories on nature and chemistry. The history of such philosophical theories that relate to chemistry, can probably be traced back to every single ancient civilization. The common aspect in all these theories was the attempt to identify a small number of primary elements that make up all the various substances in nature. Substances like air, water, and soil/earth, energy forms, such as fire and light, and more abstract concepts such as ideas, aether, and heaven, were common in ancient civilizations even in absence of any cross-fertilization; for example in Greek, Indian, Mayan, and ancient Chinese philosophies all considered air, water, earth and fire as primary elements.

Atomism can be traced back to ancient Greece and ancient India.^[1] Greek atomism dates back to 440 BC, as what might be indicated by the book De Rerum Natura (The Nature of Things)^[2] written by the Roman Lucretius^[3] in 50 BC. In the book was found ideas traced back to Democritus and Leucippus, who declared that atoms were the most indivisible part of matter. This coincided with a similar declaration by Indian philosopher Kanada in his Vaisheshika sutras around the same time period. ^[1] Kashyapa may have arrived at his sutras by meditation. By similar means discussed the existence of gases. What Kanada declared by sutra, Democritus declared by philosophical musing. Both suffered from a lack of empirical data. Without scientific proof, the existence of atoms was easy to deny. Aristotle opposed the existence of atoms in 330 BC; and the atomism of the Vaisheshika school was also opposed for a long time.

Much of the early development of purification methods is described by Pliny the Elder in his Naturalis Historia. He made attempts to explain those methods, as well as making acute observations of the state of many minerals.

The rise of metallurgy

It was fire that led to the discovery of glass and the purification of metals which in turn gave way to the rise of metallurgy. During the early stages of metallurgy, methods of purification of metals were sought, and gold, known in ancient Egypt as early as 2600 BCE, became a precious metal. The discovery of alloys heralded the Bronze Age. After the Bronze Age, the history of metallurgy was marked by which army had better weaponry. Countries in Eurasia had their heyday when they made the superior alloys, which, in turn, made better armour and better weapons. This often determined the outcomes of battles.

Indian metallurgy and alchemy

Significant progress in metallurgy and alchemy was made in ancient India. Will Durant wrote in The Story of Civilization I: Our Oriental Heritage:

The philosopher's stone and the rise of alchemy

"Renel the Alchemist", by Sir William Douglas, 1853

Many people were interested in finding a method that could convert cheaper metals into gold. The material that would help them do this was rumored to exist in what was called the philosopher's stone. This led to the protoscience called alchemy. Alchemy was practiced by many cultures throughout history and often contained a mixture of philosophy, mysticism, and protoscience.

Alchemy not only sought to turn base metals into gold, but especially in a Europe rocked by bubonic plague, there was hope that alchemy would lead to the development of medicines to improve people's health. The holy grail of this strain of alchemy was in the attempts made at finding the elixir of life, which promised eternal youth. Neither the elixir nor the philosopher's stone were ever found. Also, characteristic of alchemists was the belief that there was in the air an "ether" which breathed life into living things. Practitioners of alchemy included Isaac Newton, who remained one throughout his life.

Problems encountered with alchemy

There were several problems with alchemy, as seen from today's standpoint. There was no systematic naming system for new compounds, and the language was esoteric and vague to the point that the terminologies meant different things to different people. In fact, according to The Fontana History of Chemistry (Brock, 1992):

The language of alchemy soon developed an arcane and secretive technical vocabulary designed to conceal information from the uninitiated. To a large degree, this language is incomprehensible to us today, though it is apparent that readers of Geoffery Chaucer's Canon's Yeoman's Tale or audiences of Ben Jonson's The Alchemist were able to construe it sufficiently to laugh at it.^[4]

Chaucer's tale exposed the more fraudulent side of alchemy, especially the manufacture of counterfeit gold from cheap substances. Soon after Chaucer, Dante Alighieri also demonstrated an awareness of this fraudulence, causing him to consign all alchemists to the Inferno in his writings. Soon after, in 1317, the Avignon Pope John XXII ordered all alchemists to leave France for making counterfeit money. A law was passed in England in 1403 which made the "multiplication of metals" punishable by death. Despite these and other apparently extreme measures, alchemy did not die. Royalty and privileged classes still sought to discover the philosopher's stone and the elixir of life for themselves.^[5]

There was also no agreed-upon scientific method for making experiments reproducible. Indeed many alchemists included in their methods irrelevant information such as the timing of the tides or the phases of the moon. The esoteric nature and codified vocabulary of alchemy appeared to be more useful in concealing the fact that they could not be sure of very much at all. As early as the 14th century, cracks seemed to grow in the facade of alchemy; and people became sceptical. Clearly, there needed to be a scientific method where experiments can be repeated by other people, and results needed to be reported in a clear language that laid out both what is known and unknown.

From alchemy to chemistry

Early chemists

Jabir ibn Hayyan (Geber), an Arabic alchemist whose experimental research laid the foundations for chemistry.

The development of the modern scientific method was slow and arduous, but an early scientific method for chemistry began emerging among early Muslim chemists, beginning with the 9th century chemist Jabir ibn Hayyan (known as "Geber" in Europe), who is "considered by many to be the father of chemistry".^[6]^[7]^[8]^[9] He introduced a systematic and experimental approach to scientific research based in the laboratory, in contrast to the ancient Greek and Egyptian alchemists whose works were often allegorical and unintelligble.^[10] He also invented and named the alembic (al-anbiq), chemically analyzed many chemical substances, composed lapidaries, distinguished between alkalis and acids, and manufactured hundreds of drugs.^[11]

Among other influential Muslim chemists, Ja'far al-Sadiq,^[12] Alkindus,^[13] Ab? al-Rayh?n al-B?r?n?,^[14] Avicenna^[15] and Ibn Khaldun refuted the practice of alchemy and the theory of the transmutation of metals; and Tusi described an early version of the conservation of mass, noting that a body of matter is able to change but is not able to disappear.^[16] Rhazes refuted Aristotle's theory of four classical elements for the first time and set up the firm foundations of modern chemistry, using the laboratory in the modern sense, designing and describing more than twenty instruments, many parts are still in use today. Such as a crucible, decensory, cucurbit or retort for distillation, and the head of a still with a delivery tube (ambiq, Latin alembic), various types of furnace or stove.^[17]

Agricola, author of De re metallica

For the more honest practitioners in Europe, alchemy became an intellectual pursuit after early Arabic alchemy became available through Latin translation, and 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 was not perfect in making his experiments truly scientific. For example, as an extension of his theory that new compounds could be made by combining mercury with sulfur, he once made what he thought was "oil of sulfur". This was actually dimethyl ether, which had neither mercury nor sulfur.

Practical attempts to improve the refining of ores and their extraction to smelt metals was an important source of information for early chemists, among them Georg Agricola, who publsihed his great work De re metallica in 1556. His approach removed the mysticism associated with the subject, creating the practical base upon which others could build. The work describes the many kinds of furnace used to smelt ore, and stimulated interest in minerals and their composition. It is no coincidence that he gives numerous references to the earlier author, Pliny the Elder and his Naturalis Historia.

Robert Boyle, one of the co-founders of modern chemistry through his use of proper experimentation, which further separated chemistry from alchemy

Robert Boyle (1627?1691) is considered to have refined the modern scientific method for alchemy and to have separated chemistry further from alchemy. Robert Boyle was an atomist, but favoured the word corpuscle over atoms. He comments that the finest division of matter where the properties are retained is at the level of corpuscles.

Boyle was credited with the discovery of Boyle's Law. He is also credited for his landmark publication The Sceptical Chymist, where he attempts to develop an atomic theory of matter, with no small degree of success. Despite all these advances, the person celebrated as the "father of modern chemistry" is Antoine Lavoisier who developed his law of Conservation of mass in 1789, also called Lavoisier's Law. With this, Chemistry was allowed to have a strict quantitative nature, allowing reliable predictions to be made.

Antoine Lavoisier

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

Although the archives of chemical research draw upon work from ancient Babylonia, Egypt, and especially the Arabs and Persians after Islam, modern chemistry flourished from the time of Antoine Lavoisier, who is regarded as the "father of modern chemistry", particularly for his discovery of the law of conservation of mass, and his refutation of the phlogiston theory of combustion in 1783. (Phlogiston was supposed to be an imponderable 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

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 W�hler'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.

Disputes about atomism after Lavoisier

Bust of John Dalton by Chantrey

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.^[18] Although such proponents of the atomic theory as Amedeo Avogadro and Ludwig Boltzmann made great advances in explaining the behavior 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.^[18]

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 anticipated ideas about atomic substructure that did not fully develop until the 20th century. Michael Faraday was another early worker, whose major contribution to chemistry was electrochemistry, in which (among other things) a certain quantity of electricity during electrolysis or electrodeposition of metals was shown to be associated with certain quantities of chemical elements, and fixed quantities of the elements therefore with each other, in specific ratios. These findings, like those of Dalton's combining ratios, were early clues to the atomic nature of matter.

The periodic table

Dmitri Mendeleev, responsible for 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 in understanding the internal structure of atoms as discussed below) 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.

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 which 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 radioactivity, scientists had to change 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 radiation 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 accurate.

Quantum chemistry

Some view the birth of quantum chemistry in the discovery of the Schr�dinger equation and its application to hydrogen atom in 1926. However, the 1927 article of Walter Heitler and Fritz London^[19] 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, and thus to the phenomenon of the chemical bond. In the following years much progress was accomplished by Edward Teller, Robert S. Mulliken, Max Born, J. Robert Oppenheimer, Linus Pauling, Erich H�ckel, 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:^[20]

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.^[21] 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 extensive, 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, observations, and recipes than rigorous ab initio quantitative methods.

Diagrammatic representation of some key structural features of DNA

This heuristic approach triumphed in 1953 when James Watson and Francis Crick deduced the double helical structure of DNA by constructing models constrained by and informed by the knowledge of the chemistry of the constituent parts and the X-ray diffraction patterns obtained by Rosalind Franklin.^[22] This discovery lead to an explosion of research into the biochemistry of life.

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. Though many questions remain about the true nature of the origin of life, this was the first attempt by chemists to study hypothetical processes in the laboratory under controlled conditions.

In 1983 Kary Mullis devised a method for the in-vitro amplification of DNA, known as the polymerase chain reaction (PCR), which revolutionized the chemical processes used in the laboratory to manipulate it. PCR could be used to synthesize specific pieces of DNA and made possible the sequencing of DNA of organisms, which culminated in the huge human genome project.

Chemical industry

The later part of the nineteenth century saw a huge increase in the exploitation of petroleum extracted from the earth for the production of a host of chemicals and largely replaced the use of whale oil, coal tar and naval stores used previously. Large scale production and refinement of petroleum provided feedstocks for liquid fuels such as gasoline and diesel, solvents, lubricants, asphalt, waxes, and for the production of many of the common materials of the modern world, such as synthetic fibers, plastics, paints, detergents, pharmaceuticals, adhesives and ammonia as fertilizer and for other uses. Many of these required new catalysts and the utilization of chemical engineering for their cost-effective production.

In the mid-twentieth century, control of the electronic structure of semiconductor materials was made precise by the creation of large ingots of extremely pure single crystals of silicon and germanium. Accurate control of their chemical composition by doping with other elements made the production of the solid state transistor in 1951 and made possible the production of tiny integrated circuits for use in electronic devices, especially computers, which revolutionized the world.