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460
460 Democritus
Democritus was a greek Philosopher who roposed that matter was made up of small, hard, indivisible particles, which he called atoms. But he had no prrof to show this, thus no one believed him. -
1803-1808 John Dalton
John Dalton also proposed is composed of tiny indivisible particles called atoms, but showed evidence through the Law of Mass Conservation, Law of Constant Composition and the Law of Multiple Proportions . -
Joseph J Thompson
By using the "Plum Pudding" model, Joseph J Thompson showed that atoms consist of a large sphere of uniform positive charge(protons) embedded with smaller negatively charged particles(electrons and the total positive charge of the sphere equals the total negative charge of the negatively charged particles -
Ernest Rutherford
Earnest Rutherford proposed a nuclear model of the atom in which the a very small amount of positively charged nucleaus contains most of the mass of the atom. He later hypothesised the existence of a neutral particle in the nucleus to make up for the calculated mass deficiency in the atoms studied. -
Niels Bohr
Niels Bohr proposed a 'planetary' model for the hydrogen atom.
He also discovered that electrons orbits around the nucleaus. -
James Chadwick
James Chadwick proposed that the nucleus of an atom contains neutrons, electrically neutral particles with a mass similar to that of a proton.
