Boyle - Proposes some substances cannot be made smaller
Dalton - Suggests elements are made up of atoms, and different atoms have different masses
Becquerel - Discovers radioactivity, showing particles can come from inside an atom
JJ Thompson - Discovers electrons and negative charge, also suggests plum pudding model
Rutherford - Found that atoms are made up of sub-atomic particles.
Protons - Positive charge, Mass 1, found in nucleus
Neutrons - No charge, Mass 1, found in nucleus
Electrons - Negative charge, orbits the nucleus in shells, negligible mass
Arrangement of Electrons
1913 - Bohr suggests that atoms are like small solar systems with electrons orbiting a positive nucleus.
1932 - Chadwick discovers the neutron.