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430 BCE
Democritus
In this time Democritus proposed the first idea of the atom. He proposed that atoms are substances made up of tiny invisible particles called 'atomos" -
LaVoisier
this man introduced the Law of Conservation of Mass. Which was that matter could not be created or destroyed, that it can only simply be rearranged. -
Period: to
John Dalton
Proposed the first Atomic Theory consisting that all matter is made up of tiny invisible atoms, atoms of the same element are the same, atoms with different elements are different and atoms combine in whole number ratios to form compounds. (Dalton's Model) -
JJ Thompson
The 'plum pudding' model of the atom was proposed by JJ Thomson, who had also discovered the electron. It was put forth before the discovery of the nucleus. -
Albert Einstein
Albert Einstein had came up with the "Photoelectric Effect". Which was that when a certain frequency shines on a metal, electrons are emitted. -
Ernest Rutherford
Rutherford atomic model, also called nuclear atom or planetary model of the atom, description of the structure of atoms proposed (1911) by the New Zealand-born physicist Ernest Rutherford. -
Niels Bohr
introduced by Niels Bohr and Ernest Rutherford in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar to the structure of the Solar System -
James Chadwick
James Chadwick played a vital role in the atomic theory, as he discovered the Neutron in atoms. Neutrons are located in the center of an atom, in the nucleus along with the protons.