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23 Jan 2018
(400 B.C.) Democritus Theory: everything is composed of atoms which are physically but not geometrically indivisible
(1766) Dalton's Theory: - all matter is made of atoms that are indivisible and indestructible - compounds are formed by combinations of atoms
(1844) Thompson discovered atoms weren't the smallest things and Dalton's model ended.
(1904) Thompson created the "Plum-Pudding" model where electrons are surrounded by a "soup" of positive charge
(1911) Rutherford's Theory (nuclear): An atom is mostly empty space, with electrons orbiting a fixed positively charged nucleus in set, predictible
(1926) Quantum Mechanic Model: - this theory states that it is impossible to know the exact location of an electron while also knowing the momentum of it at the same time - model uses electron cloud to show where electron is likely to be
(1913) Niels Bohr Theory (planetary): the atom is made of a small positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus
(1932) Chadwick's Neutron: - discovered the sub-atomic particle the neutron - his model shows a nucleus made of protons and neutrons
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