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400
Democritus
stated that all matter is made up of atoms. He also stated that atoms are eternal and invisible and so small that they can’t be divided, and they entirely fill up the space they’re in. -
Period: to
history of atom
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Lavoisier
He provided the formula for the conservation of matter in chemical reactions, and also compared between an element and a compound. -
Charles Couloumb
Made a law that the force between two eletrical charges and inersely distance between them, one of the main forces involved in atomic reactions. -
John Dalton
formed the atomic theory, which he made out that the matter is made up of tiny, indestructible particles called atoms that are all alike and have the same atomic weight. -
j.j Thomson
discovered the electron and developed the "plum-pudding" model of the atom. -
Robert Millikan
discovered the electric charge of the electron -
Ernest Rutherford
used the results of his gold-foil experiment to state that all the mass of an atom were in a small positively-charged ball at the center of the atom. -
Neils Bohr
Figured that the electrons moved around the nucleus in large orbits. He also presented the Bohr atomic model which stated that atoms absorb or emit radiation only when the electrons abruptly jump between different atoms -
Geiger
Made the first detector of alpha particles -
Chadwick
discovered the neutrally-charged neutron. -
Otto Hahn
discovered nuclear fission, in which the nucleus in an atom breaks up into two separate nuclei, while experimenting with uranium. -
Glen T. Seaborg
isolated and identified elements heavier than uranium, and in the process, added elements number 94 - 102, and 106. -
Murray Gell-Mann and George Zweig
brought forth the idea of "quarks", little bits of matter which when used kind of like building blocks, serve to explain some complex chemical substances.
