Democritus was a Greek scientist that hypothesized the existence of atoms and their being indivisible and indestructable.
Aristotle was a Greek scientist that rejected Democritus' idea as he thought that matter was continuous.
Dalton was a English scientist that came up with the atomic theory
Crookes was a British scientist that developed the cathode ray tube
Thompson was a British scientist that showed that the "cathode ray" which traveled from cathode(-) to anode (+) was electrons in 1897. Thompson also discovered electrons and developed the plum pudding model.
Millikan was an American scientist that found the charge on an electron to be 1.602 x 10^ -19 Coulobmbs and found the mass of an electron to be 9.11 x 10^ -28
Rutherford was an English scientist that conducted the gold foil experiment which led to the concept of the nucleus. Therefore, Rutherford discovered the nucleus and also developed the nuclear model.
Bohr was a Danish scientist that found that hydrogen absorbs energy then releases it at a specific frequency
Moseley was an English scientist that found that atoms have a special and unique charge
Chadwick was an English scientist that discovered the existence of neutrons.