| A | B |
|---|
| Democritus | Thought of indivisible “atomos” |
| Ernest Rutherford | Developed the nuclear model |
| Hantaro Nagaoka | Developed the Saturnian model |
| J.J. Thomson | Developed the plum pudding model |
| John Dalton | First suggested that elements are made of atoms and of an element are all alike |
| Niels Bohr | Believed that electrons move through spherical regions located a fixed distance from the nucleus |
| Chadwick | discovered the neutron |
| Proton | The quantity of this subatomic particle in an atom of a substance determines the atom’s identity. |
| Electron | his subatomic particle is the smallest of the three. |
| Neutron | This subatomic particle is found in the nucleus and has no electrical charge. |
| isotopes | atoms of the same element with differing numbers of neutrons |
| cation | An ion that has more protons than electrons |
| anion | An ion that has less protons than electrons |
