| A | B |
|---|
| Democritis | A Greek philosopher who stated that matter is made up of tiny indivisible particles called "atoms." |
| John Dalton | An atom is a sphere with it's own characteristic mass. |
| J.J. Thompson | In his model, negatively charged particles called electrons are embedded in a sphere of postive charge. |
| Ernest Rutherford | The atom consists of a small core that contains most of the mass of the atom. This nucleus is made up of protons. The protons are surrounded by negatively charged electrons; but most of the atom is empty space. |
| Niels Bohr | Electrons travel around the nucleus of an atom in orbits. |
| James Chadwick | The neutron is also in the nucleus and has no charge. |
