This scientist thought that movements of atoms caused the changes in matter
Who is Democritus
200
The law of deifinite proportions states a chemical compound always contains the same amount elements in exactly the same proportions by weight or mass, according to...
Who is Dalton
300
The sum of the numbers of protons and neutrons in the nucleus of an atom
What is mass number
300
It was in this year that scientist J.J. Thomson conducted an experiment that suggested atoms were not indivisible
What is 1897
400
The SI base unit used to measure the amount of a substance