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400 BCE
Democritus
Democritus theorizes atoms exist. He named them atoms because in Greek "atomos" means "uncut". He thought atoms were invisible and were the shape of whatever they makeup. -
John Dalton
John Dalton thought that all matter was made up of atoms,
all atoms of an element had a fixed mass,
compounds contain atoms from different elements, and in compounds atoms from different elements always combine in a specific way. This is a picture of what he thought atoms looked like. -
Marie Curie
Marie Curie discovered Radium, Plutonium, and coined the term "radioactivity". Unfortunately because she was a woman her husband got all of the credit. -
E. Goldstein
Goldstein discovered protons using anode rays. He said that protons and electrons balanced each other out and that electrons madeup electricity. -
J.J. Thompson
Thompson used Cathode rays to discover electrons and said they were organized like plum pudding. -
Robert Millikan
Millkan discovered that electrons have a negative charge. -
Ernest Rutherford
Rutherford discovered the nucleus of atoms by reflecting particles off gold foil. -
Niels Bohr
Stated that electrons orbit at a fixed distance from the nucleus. -
James Chadwick
Proved the nucleus existed and stated it was made of protons and neutrons and that neutrons have no charge. -
Quantum Mechanical Model (aka Wave Model)
Erwin ShrÖdinger discovered electrons have no set path and created the model used today.
