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500 BCE
The Alchemists
The Alchemists made the theory that all metals are made of sulfur and mercury and they could all be changed into gold. He thought that all atoms were made of different weights and can form into simple ratios by weight. -
427 BCE
Plato
He introduced how geometric forms serve as atoms. -
400 BCE
Democritus
Democritus was one of the first to realize that everything is made of atoms -
322 BCE
Aristotle
His theory was that everything was made of non visible things called atoms. -
Robert Boyle
He helped make a definition for an element -
Lavoisier
Lavoisier discovered how mass is conversed in a chemical reaction. -
John Dalton
Dalton had a atomic theory that suggested that all matter was made of atoms, non visible, immortal building blocks. -
Dmitri Mendeleev
He made the first Periodic Table. He found that all the chemical elements were arranged in order of uprising atomic weight. -
The Curies
The Curies discovered the radioactive elements radium and polonium. -
J.J. Thomson
J.J. Thomson determined the electron was an important part of the atom. -
Albert Einstein
He proved the existence of atoms. He introduced the atomic equation E=mc2. He discovered that mass and energy cannot be changed. -
Robert Millikan
Millikan discovered how electricity was made by a minuscule unit which is the electron. -
Ernest Rutherofrd
Rutherford made the discovery of alpha and beta rays and suggested the laws of radioactive decomposition. -
Niels Bohr
Niels Bohr made a theory for the hydrogen atom based on quantum theory. -
Henry G. J. Moseley
Moseley discovered a systemic connection between atomic number and wave length. -
Werner Heisenberg
Heisenberg discovered that a particle's momentum and location both cannot be known.
