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Democritus
Democritus was a Greek philosopher, who proposed the idea that matter is made of tiny, indivisible, indestructable -
John Dalton
John Dalton's theory is called Dalton's atomic theory. It is impossible to divide or destroy an atom because it is so small. Dalton was an English chemist that discovered an atom. Atoms of different elements join together. They have ratios that tell you how many of each element is in the compound.Example; 2:1 there are 2 hydrogen and 1 oxygen atom. -
J.J Thompson
J.J Thompson was an English scientist that discovered the electron.Electrons are the particles in an atom that have a negative charge. When he discovered the electron, he was experimenting with gas discharge tubes. When he noticed a movement in the tube, he called it cathode rays.They moved from the negative to he positive ends of the tube. -
Niels Bohr
Neils Bohr was a danish physicist. He proposed a model of the atom that looks like the solar system. The electrons orbit around the nucleus like planets on shells or rings. All electrons have their energy level or their certain distance from the nucleus. His model was also called the planetary model of an atom. The furthest shell can hold 32 electrons and the closest shell can hold 2 electrons. Every electron has a different energy level. -
Lord Ernest Rutherford
Lord Ernest Rutherford conducted a famous experiment called the gold foil experiment. In his experiment, he used a thin sheet of gold foil. When he put the foil in the front of the particles, most of them just passed through it like like it was not there. The other particles went straight back or were deflected, as if they hit something. Atoms are made of a small positive nucleus; positive nucleus repels (pushes away) positive alpha particles. Also, he figured out that atoms are mostly empty.
