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400 BCE
Democratus
He adopted the atomic theory in the 400 B.C. The atomic theory is stated to be that"the universe is composed of two elements: the atoms and the void in which they exist and move." -
John Dalton
He was an English Chemist, physicist, and meteorologist. Best known for proposing the modern atomic theory and his research into color blindness, Daltonism. 19th century is when this occurred. (Pioneering theory of atomism) -
J.J. Thompson
He was an english scientist. When he was experimenting with gas discharge tubes he discovered the electron. The electron has a negative charge. During the experiment there had been movement and what he called cathode rays had been moving from the negative side to the positive side and so it was bouncing or getting away from negative side. Which must have made the rays negatively charged particles. Like a magnet almost, the opposite sides attract and the same sides repel. -
Niels Bohr
He was a Danish physicist. He proposed a model that was similar to the solar system. In which this model could be called the planetary model. This model had 4 levels, each level increasing in electrons. The electrons were used to go around the nucleus like the planets go around the sun. -
Lord Ernest Rutherford
Rutherford studied in the fields of radioactivity and nuclear physics. He conducted a famous experiment called the gold foil experiment. He discovered alpha and beta rays, set forth the laws of radioactive decay, and that alpha particles are helium nuclei.
