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He was the first person to suggest that matter could not be infinitely divided. He came up with the name atom. He couldn't figure out what holds the atom together.
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Dalton took Democritus' ideas and created the phrase "Atoms are the smallest particles of matter and are invisible and indestructible."
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He designed a series of Crt experiments to determine the ratio of the particle's charge to mass.
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He designed an oil drip apparatus to determine the charge of the electron. He also determined that the magnitude of the charge of the electron was 1.602x10^-19 coulombs. He also discovered the mass of the electron using the known charge/mass ratio: 9.1x10^-28 g. He made the Plum Pudding Model.
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Rutherford tested the Plum Pudding Model and found that some a-particles bounced back, therefore causing the model to be incorrect. He studied how positively charged a-particles interacted with solid matter. He came to the conclusion that there had to be a place for the positive charge and the majority of the mass of an atom to reside. Because he realized this, he discovered the nucleus.
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James Chadwick found that the nucleus had another neutral subatomic particle. He won a nobel piece prize for discovering the nuetron.
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He disagreed with Democritus' idea that atoms move through empty space. Due to personal ideas about nature, he completely denied the existence of atoms. HIs ideas took over those of Democritus.
