-
Democritus Atom Democritus claimed that everything is made out of atom. They are physically indivisble and indestructible.
-
Dalton's atomic theory Dalton's theory is that all matter is made of atoms. Atoms are indivisble. A chemical reactipn is a rearrangment of atoms.
-
J.J. Thomson Thomson founded the electron in 1897.He found out atoms had smaller particles. He used a cathode ray tube. He later found out that atoms were made of protons, neutrons, and electrons.
-
Rutherford Rutherford published his theory that the atom has a central positive nucleus and negative electrons. He put out gold foil. 1 of 8000 particles went throught, thus saying that the atom is mostly empty.
-
James Chadwick Chadwick predicted there would be a neutron. He established that the number of protons is the atomic number.
-
Niels Bohr Niels Bohr won a Nobel in 1922. He later was the first one to discover that electrons travel in different orbit around the nucleus.
