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101
democcritus
year 101The theory of Democritus and Leucippus held that everything is composed of "atoms", which are physically, but not geometrically, indivisible; that between atoms lies empty space; that atoms are indestructible; have always been, and always will be, in motion; that there are an infinite number of atoms, and kinds of atoms, which differ in shape, and size. -
john dalton
n 1800, Dalton became a secretary of the Manchester Literary and Philosophical Society, and in the following year he orally presented an important series of papers, entitled "Experimental Essays" on the constitution of mixed gases; on the pressure of steam and other vapours at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases. These four essays were published in the Memoirs of the Lit & Phil in 1802. -
jj thompson
Thomson, in 1897, was the first to suggest that the fundamental unit was over 1000 times smaller than an atom, suggesting the subatomic particles now known as electrons. -
Werner Heisenberg & Erwin Schrodinger
In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to Naturwissenschaften reporting they had detected the element barium after bombarding uranium with neutrons; simultaneously, they communicated these results to Lise Meitner, who had in July of that year fled to the Netherlands and then went to Sweden.The first publications of Schrödinger about atomic theory and the theory of spectra began to emerge only from the beginning of the 1920s, after his perso -
Hantaro Nagaoka
The model made two predictions: a very massive nucleus (in analogy to a very massive planet) electrons revolving around the nucleus, bound by electrostatic forces (in analogy to the rings revolving around Saturn, bound by gravitational forces). -
Neils Bohr
Bohr worked on the Manhattan Project at the top-secret Los Alamos laboratory in New Mexico, where he was known by the name of Nicholas Baker for security reasons.[23] His role on the project was as the knowledgeable consultant or "father confessor". He often expressed social concern about such weaponry and an eventual nuclear arms race, and is quoted as saying, "That is why I went to America. They didn't need my help in making the atom bomb." -
ernest rutherford
the first person to deliberately transmute one element into another. In this experiment, he had discovered peculiar radiations when alphas were projected into air, and narrowed the effect down to the nitrogen, not the oxygen in the air. Using pure nitrogen, Rutherford used alpha radiation to convert nitrogen into oxygen through the nuclear reaction -
James Chadwick
n 1932 Chadwick discovered a previously unknown particle in the atomic nucleus. He communicated his findings in detail. This particle was first predicted by Ettore Majorana and has come to be known as the neutron because of its lack of electric charge. Chadwick's discovery was crucial for understanding the nuclear fission of uranium 235
