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460 BCE
Democritus
Democritus said that all matter was made of atoms that are surrounded by empty space. He didn't do a lot of research or test his theory much. -
John Dalton
Agreed with Democritus' ideas and also added that atoms were indestructible. He came up with the idea that compounds were created when two atoms were combined. Also when elements are identical so are their mass and properties. -
J.J. Thomson
Developed the Plum Pudding Model. The model explains that electrons are surrounded by positive charges to balance the negative ones. Also, he notices the electrons and found out the atom can be divided. -
Ernest Rutherford
Discovered the nucleus. Took gold foil and threw particles through it and some returned while others disappeared proving his theory that atoms are also made up of empty space. Also, he learned that there's two kinds of radiation, "alpha" and "beta." He called his discovery the nuclear atom after realizing there was a nucleus inside. -
Niels Bohr
Made the Planetary Model in 1913. Shows that the nucleus is surrounded by electrons at different levels of energy. He also perfected Planck's Quantum Energy Theory.
