International Year of Chemistry: A History of Chemical Sciences

Antoine Lavoisier's famous phlogiston experime...

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By A.N.Khan

The author is National Award winning Scientist and Former Assistant Director, National Environmental Engineering Research Institute, Nagpur.

New Delhi, Sep 19, 2011 (Washington Bangla Radio / PIB India) United Nations Organization has declared 2011, as the ‘International Year of Chemistry”.  It is  to honour the completion of 100 years of awarding the Nobel prize in chemistry to Marie Curie (1867 - 1934) who  discovered a new radio-active element called polonium. She was often ill due to her excessive exposure to radioactive rays and died at the age of 61 due to Leukemia.  The year is to remember great scientists who sacrificed their lives for the service of the mankind through science.

The year 2011 also completes the successful hundred years of the ‘International Association of Chemical Societies’.  The United Nation’s Educational Scientific and Cultural Organization (UNESCO) and International Union for Pure and Applied Chemistry (IUPAC) have jointly accepted the responsibility of successfully celebrating 2011 as International Year of Chemistry.  The main theme is ‘Chemistry for Mankind : Innovative Ideas in Life Sciences’.

Inventions in Chemistry has given innumerable application to mankind – starting from manufacturing oxygen, water, food, building materials, medicines, and progressive economic development of mankind.  Chemistry, thus, has become an integral part of the human race.

Upto 17th century, chemistry was not treated as independent branch of science.  It gained considerable recognition as modern chemistry with the efforts of Antoine Lavoisier.

Antonie Laurent Lavoisier (1743-1794) is considered to be the father of modern chemistry.  He is most noted for his discovery of the role oxygen plays in combustion.  Lavoisier introduced the method of naming the chemical compounds which are still used.  In 1789 his main contributions to chemistry were elegantly set out in his ‘Elementary Treatise on Chemistry’

On November 1, 1772, Lavoisier deposited with the Academy, a note which stated that sulphur and phosphorus, when burnt increased in weight because they absorbed ‘air’, while the metallic lead formed from litharge by reduction with charcoal weighed less than the original litharge because it had lost ‘air’.  The exact nature of air, concerned in the process he did not explain until after the preparation of ‘dephlogisticated air’ (oxygen) by Joseph Priestley in 1774.  In a memorier presented to the Academy in 1777, but not published until 1782, he assigned to dephlogisticated air the name oxygen or ‘acid producer’, on the erroneous supposition that all acids were formed by its union with a simple, usually non-metallic body. Combustion was explained by Lavoisier not as the result of liberation of hypothetical ‘phlogiston’, but as the result of the combination of the burning substance with oxygen.  On June 25, 1783, in conjunction with Pierre Laplace, he announced to the Academy that water was the product formed by the combination of hydrogen and oxygen; by that time he had been anticipated by Henry Cavendish.  From his knowledge of the composition of water Lavoisier led to the beginnings of the quantitative organic analysis.  He burnt alcohol, and other combustible organic compounds, in oxygen and from the weight of water and carbon dioxide produced, calculated their composition.

Oxygen was first prepared around  1772 by K.W. Scheele by heating certain metals oxides, including mercury oxide, and was discovered independently in 1774 by Joseph Priestley, who also obtained it by heating mercuric oxide.  Its recognition as a chemical element is, however, due to Lavoisier (1775-77).  The chemical symbol is O, the atomic number 8, atomic weight 16, and serves as the standard with which the atomic weights of other elements are compared.

It is to Lavoisier that we owe to a great extent the modern concept of an element as against the old Greek idea.

By the middle of the 18th century, however, chemistry became a quantitative science based on the use of the analytical balance, and the needed chemical criteria were established.  The new and clarifying ideas on the nature of matter were published by Lavoisier in 1789, and thereafter until the later development of physical methods (e.g. x-rays), substances were classified as elements or compounds solely on the basis of their chemical reactions.

By the use of data obtained in his experimental studies of chemical reactions, Lavoisier was able to prepare the first scientific list of elements, which he published in his book in 1789.

Before the publication of John Dalton’s atomic theory and indeed even before the formal enunciation of the Law of the conservation of mass by Lavoisier, there was some recognition of the principle of equivalency in chemical combinations.

Despite all the contributions to science and France, in his 51 years of life Lavoisier was made the victim of the French Revolution.  His estate was confiscated and his library and laboratory was burnt. He was guillotined i.e., executed on 8th of May 1794.

Michael Faraday (1791-1867) discovered the laws of electrolysis which paved the way for electroplating in industries.

Carl Wilhelm Scheele (1742-1786) discovered chemical elements like chlorine, molybdenum, tungsten, manganese and many compounds. He died after tasting mercury compound in one of his experiments.

Sir Humphry Davy (1778-1829) who became blind while conducting an experiment, discovered sodium, potassium, minerals, safety lamp, laughing gas - N2O.

Robert Wilhelm Bunsen (1811-1899) was a pioneer of chemical spectroscopy. Bunsen Burner is used in every chemistry laboratory in the world. During research he lost his  eye and died of Arsenic poisoning.

Prafulla Chandra Ray (1861-1944) represented India in the field of chemistry and later came to be known as the Doyen of Chemical Sciences in India. He is credited with the discovery of Mercurous Nitrate and synthesizing Ammonium Nitrite. His research on nitrates earned him the nick name, "the Nitrate Man", in the international scientific community.  He established Bengal Chemical and Pharmaceuticals in the year 1901 with a view to utilising science for generating employment and livelihood for the unemployed youth. Ray was a very popular teacher and some of his students like Satyendra Nath Bose and Meghanad Saha were destined to play a very important part in the future scientific research work in India. Ray lived alone in a single room in the university college of science, Kolkata till his death on June 16, 1944.

Thus the history of chemistry is the history of human civilization recording dedication and sacrifice of many great scientists.

- PIB Features

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