-
500 BCE
The Alchemists
The Alchemists found a substance that could transmute common metals to silver and gold -
400 BCE
Democritus
Democritus proposed that all matter is made up of small indestructible units -
428
Plato
Plato discovered that there was a common element shared between earth, air, fire, and water -
Robert Boyle
Boyle discussed the existence of atoms and defined elements and compounds -
Robert Boyle
Boyle discussed the existence of atoms and defined elements and compounds. -
Antone Lavoisier
Lavoisier proved the theory of conservation of matter by measuring reactions within a sealed container -
John Dalton
John Dalton proposed the theory that compounds were made up of of combined elements -
John Dalton
Dalton proposed that compounds were composed of multiple elements combined -
Billiard ball model
Model envisioned by Dalton, who thought that atoms were small hard spheres -
Dmitri Mendeleev
Mendeleev created the first form of the periodic table -
JJ Thompson
Thompson was able to calculate the ration of charge to mass in an electron -
The Curies
The Curies discovered the radioactive elements radium and polonium -
Plum pudding model
An atomic model proposed by JJ Thompson which suggested that electrons exist within a positively charged jelly. -
Albert Einstein
Einstein was able to prove the existence of atoms by observing particles suspended in fluids -
Albert Einstein
Einstein was able to prove that atoms existed by observing small particles in fluids -
Robert Millikan
Millikan discovered the fact that electrons are negatively charged with the oil drop experiment -
Ernest Rutherford
Rutherford concluded for his experiment that atoms have a small nucleus with a positive charge -
Solar System Model
Atomic model proposed by Rutherford which stated that atoms contain a tiny, dense, positively charged nucleus which is orbited by electrons -
Neils Bohr
Neils Bohr proposed an atomic structure theory in which the outer orbit is able to hold more than the inner orbit -
Neils Bohr
Bohr proposed an atomic structure where the outer orbit can hold more than the inner orbit -
Henry G.J. Mosely
Mosely determined that the amount of protons in an atom is what determines the atomic number of said atom -
Erwin Schrodinger
Schrodinger discovered that it is possible to find the quantity of hydrogens energy with an equation called schrodinger's equation -
James Chadwich
Chadwich discovered the neutrons, which are neutrally charged particles within the atoms nucleus