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400
Democritus
Democritus of Adbera is credited for the term atomos, meaning indivisible. He was the first to identify the possibility of an atom and deem it as the smallest piece of matter. (the date can't be set in BC on timetoast, so it looks out of order, when it should be ~400BC) -MW -
Period: 400 to
atomic theory
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John Dalton
John Dalton is credited as the father of the modern atomic theory. The theory is composed of five parts, which includes elements being composed of atoms and that element's atoms are identical in mass. -
JJ Thomson
The plum pudding model, proposed by JJ Thomson, was seen as the atom before the discovery of the atomic nucleus. The model is composed of electrons surrounded by positive charge to balance the negative charges. The "plums" were neutralized by the "pudding". This model of the atom was disproved in 1909, by Ernest Rutherford -
Ernest Rutherford
Ernest Rutherford is credited with the gold foil experiment. He stated that atoms have a small positively charged nucleus, and the remainder is empty space. -
Niels Bohr
Niels Bohr is credited with the planetary model of the atom. He also stated that electrons traveled in specified energy levels and that spectrum lines are produced when electrons move. -
Werner Heisenberg
Werner Heisenburg is credited with the "uncertainty principle", which states it is impossible to determine the position and momentum of a particle at the same time. He is also credited with the "cloud" model, also known as the quantum mechanical model. -
Erwin Schrodinger
Erwin Schrodinger is credited with showing mathematically that waves can be used to describe electrons in atoms. He also determined the probability location of electrons in atoms.
