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465
Democritus
- His hypothesis was created in 465 BC
- 1.All matter consists of invisible particles called atoms.
- Atoms are indestructible.
- Atoms are solid but invisible.
- Atoms are homogenous.
- Atoms differ in size, shape, mass, position, and arrangement. ->Solids are made of small, pointy atoms. ->Liquids are made of large, round atoms. ->Oils are made of very fine, small atoms that can easily slip past each other.
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John Dalton
The most important of all Dalton's investigations are those concerned with the atomic theory in chemistry. It was proposed that this theory was suggested to him by ethylene and methane, or by analysis of nitrous oxide and nitrogen dioxide. -
JJ Thomason
JJ Thomason was the first to suggest that one of the basic units was more than 1,000 times smaller than an atom, suggesting the electron. He discovered this through his experiments on the properties of cathode rays. -
Ernest Rutherford
Rutherford created the Rutherford model of the atom in 1911, which showed how the nuclear nature of the atom deflecting the alpha particles passing through a thin gold foil. -
Niels Bohr
In 1913, "the trilogy" was published. He adapted Rutherford's nuclear structure with Max Planck's quantum theory and created his Bohr model of the atom.Taking the 1912 paper by Darwin, on the role of electrons in the interaction of alpha particles with a nucleus, he advanced the theory of electrons travelling in orbit around the atom's nucleus, with the chemical properties of each element being largely determined by the number of electrons in the outer parts of its atoms.
