-
300
Aristotle (bc)
there are only elements, not atoms
he just looked at the world -
400
Democritus (bc)
He discovered all matter is made up of tiny, indivisible particles called atoms
the microscope was his method
Atom the indvisible particle, small & hard -
Dalton
all matter is atoms, diff. masses & properties
he used chemicals as his method
rasin in the pudding, a solid lumpy sphere -
Thomson
Discoverd electrons
he used the cathode rays to create the plum pudding model
plum -
Rutherford
discoverd of atom nucleus, plantary model of the atom, and the downfall of the plum pudding model
gold leaf experiment theory
tiny planetary system, with most of the mass in the neutron and electrons, orbiting like the sun -
Bohr
2e- in first shell, 8e- in 2nd shell, 8e- in 3rd shell
calculating the diff. energy levels of the atom hrydrogen atom
showed that electrons couldn't have specific amounts of energy, leading them to move -
Heisenberg & Schrodinger
Schrödinger and Heisenberg discoverd quantum mechanics theory of quantum mechanics Each electron is a cloud, of negative charge, instead of one tiny negative particle
