FAMOUS SCIENTISTS - by Gowri & Pranav

Joseph Proust 1754 - 1826

Nationality - French Field - Chemistry

Education acquired - Proust prepared for becoming an apothecary (a person who prepared and sold medicines and drugs), first with his father in Angers and then in Paris, where he also studied chemistry with HilaireMartin Rouelle. Researches and inventions done - law of definite proportions in 1794. Main contribution to the discovery of the atom - law of definite proportions, stating that chemical compounds always combine in constant proportions Awards received - none

Ernest Rutherford 1871 - 1937

Nationality - New Zealander Field - Radioactivity, Atomic physics, Nuclear physics

Education acquired - University of New Zealand, Cavendish Laboratory, University of Cambridge Researches and inventions done - Postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay Main contribution to the discovery of the atom - In 1911, he theorised that atoms have their charge concentrated in a very small nucleus. He performed the first artificially induced nuclear reaction in 1917 in experiments where nitrogen nuclei were bombarded with alpha particles (composite particles consisting of two protons and two neutrons tightly bound together). As a result, he discovered the emission of a subatomic particle which, in 1919, he called the "hydrogen atom" but, in 1920, he more accurately named the proton. Under his leadership the neutron was discovered by James Chadwick in 1932. Awards received - Nobel Prize in Chemistry (1908), Rumford Medal (1904), Barnard Medal (1910), Elliott Cresson Medal (1910), etc

JJ Thomson 1856 - 1940

Nationality - British Field - Physics

Education acquired - Trinity College (Cambridge), Owens College (now the University of Manchester) Researches and inventions done - Discovery of electron, Discovery of isotopes, Mass spectrometer invention, Electromagnetic mass Main contribution to the discovery of the atom - Disovery of electrons. Thomson discovered this through his explorations on the properties of cathode rays. His experiments suggested not only that cathode rays were over 1,000 times lighter than the hydrogen atom, but also that their mass was the same in whichever type of atom they came from. He concluded that the rays were composed of very light, negatively charged particles which were a universal building block of atoms. He called the particles "corpuscles", but later scientists preferred the name electron. Awards received - Royal Medal (1894), Hughes Medal (1902), Nobel Prize in Physics (1906), etc.

James Chadwick 1891 - 1974

Nationality - English Field - Physics

Education acquired - University of Manchester, University of Cambridge Researches and inventions done - Discovery of neutron Main contribution to the discovery of the atom - Discovery of neutron. James Chadwick fired alpha radiation at beryllium sheet from a polonium source. This led to the production of an uncharged, penetrating radiation. He concluded that the unusually penetrating radiation consisted of uncharged particles having (approximately) the same mass as a proton. These particles were later termed ‘neutrons’. Awards received - Nobel Prize in Physics (1906), Fellow of the Royal Society (1927), Hughes Medal (1932)

L. R. A. C. Avogadro 1776 - 1856

Nationality - Italian Field - Chemistry

Education acquired - University of Turin Researches and inventions done - Molecular theory or avogadro law Main contribution to the discovery of the atom - Avogadro's law, which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. In tribute to him, the ratio of the number of elementary entities (atoms, molecules, ions or other particles) in a substance to its amount of substance (the latter having the unit mole), 6.02214076×10^-23, is known as the Avogadro constant. Awards received - Nobel Prize in Physics (1906), Fellow of the Royal Society (1927), Hughes Medal (1932)

Eugen Goldstein 1850 - 1930

Nationality - German Field - Physics

Education acquired - University of Breslau Researches and inventions done - Discovery of canal rays. In 1886, he discovered that a Crookes tube with a perforated cathode also emit a glow at the cathode end. Goldstein concluded that in addition to the already-known cathode rays, later recognized as electrons moving from the negatively charged cathode toward the positively charged anode, there is another ray that travels in the opposite direction. Because these latter rays passed through the holes, or channels, in the cathode, Goldstein called them canal rays.

Main contribution to the discovery of the atom - He discovered several important properties of cathode rays, which contributed to their later identification as the first subatomic particle, the electron. He found that cathode rays were emitted perpendicularly from a metal surface, and carried energy. Awards received - Hughes Medal

Niels Bohr 1885 - 1962 Alma mater Kingdom of Denmark

Nationality - Danish Field - Theoretical physics

Education acquired - University of Copenhagen Researches and inventions done - Made foundational contributions to understanding atomic structure and quantum theory Main contribution to the discovery of the atom - Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. Awards received - Nobel Prize in Physics (1922)

John Dalton 1766 - 1844

Nationality - English Field - Chemistry and Physics

Education acquired - United Kingdom of Great Britain and Ireland Researches and inventions done - Atomic theory and Dalton's law ( or law of multiple proportions) Main contribution to the discovery of the atom - Atomic theory. Postulates from Dalton’s atomic theory are: The matter is made up of tiny indivisible particles called atoms. Atoms can neither be created nor destroyed. Atoms of a given element are identical in size, mass, and other properties. Atoms of different elements differ in size, mass, and other properties. Atoms combine in simple whole-number ratios to form compounds. In chemical reactions, atoms are combined, separated, or rearranged. Awards received - Royal Medal (1826), Fellowship of the Royal Society (1822)

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