PRESENTATION OUTLINE
CONTIBUTION OF SCIENTISTS IN THE PERIODIC TABLE
ANTOINE-LAURENT DE LAVOISIER
Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution; 26 August 1743 – 8 May 1794; French pronunciation: [ɑ̃twan lɔʁɑ̃ də lavwazje]) was a French nobleman and chemist central to the 18th-century Chemical Revolution and a large influence on both the histories of chemistry and biology.He is widely considered to be the "Father of Modern Chemistry."
It is generally accepted that Lavoisier's great accomplishments in chemistry largely stem from the fact that he changed the science from a qualitative to a quantitative one. Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783) and opposed the phlogiston theory. Lavoisier helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. He predicted the existence of silicon (1787)and was also the first to establish that sulfur was an element (1777) rather than a compound.He discovered that, although matter may change its form or shape, its mass always remains the same.
JOHANN WOLFGANG DÖBEREINER
Döbereiner discovered trends in certain properties of selected groups of elements. For example, the average atomic mass of lithium and potassium was close to the atomic mass of sodium. A similar pattern was found with calcium, strontium, and barium, with sulfur, selenium, and tellurium, and also with chlorine, bromine, and iodine. Moreover, the densities for some of these triads followed a similar pattern. These sets of elements became known as "Dobereiner's Triads"
Alexandre-Émile Béguyer de Chancourtois
Alexandre-Émile Béguyer de Chancourtois (20 January 1820 – 14 November 1886) was a French geologist and mineralogist who was the first to arrange the chemical elements in order of atomic weights, doing so in 1862. De Chancourtois only published his paper, but did not publish his actual graph with the proposed arrangement. Although his publication was significant, it was ignored by chemists as it was written in terms of geology. It was Dmitri Mendeleev's table published in 1869 that became most recognized. De Chancourtois was also a professor of mine surveying, and later geology at the École Nationale Supérieure des Mines de Paris. He also was the Inspector of Mines in Paris, and was widely responsible for implementing many mine safety regulations and laws during the time.
In 1862, a year before John Alexander Reina Newlands published his classification of the elements, de Chancourtois created a fully functioning and unique system of organizing the chemical elements. His proposed classification of elements was based on the newest values of atomic weights obtained by Stanislao Cannizzaro in 1858. De Chancourtois devised a spiral graph that was arranged on a cylinder which he called vis tellurique, or telluric helix because tellurium was the element in the middle of the graph. De Chancourtois ordered the elements by increasing atomic weight and with similar elements lined up vertically.
DMITRI IVANOVICH MENDELEEV
Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created his own version of the periodic table of elements, and used it to correct the properties of some already discovered elements and also to predict the properties of eight elements yet to be discovered.
HENRY GWYN JEFFREYS MOSELEY
Henry Gwyn Jeffreys Moseley was an English physicist. Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra. Moseley's Law justified many concepts in chemistry by sorting the chemical elements of the periodic table of the elements in a quite logical order based on their physics.
Sir William Ramsay KCB FRS FRSE was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous elements in air" (along with his collaborator, Lord Rayleigh, who received the Nobel Prize in Physics that same year for their discovery of argon). After the two men identified argon, Ramsay investigated other atmospheric gases. His work in isolating argon, helium, neon, krypton and xenon led to the development of a new section of the periodic table.
