| A | B |
|---|
| Nucleus | the center of an atom; made up of protons and neutrons |
| proton | A positively charged subatomic particle in the nucleus |
| Neutron | a neutral subatomic particle in the nucleus of an atom |
| Electron | A tiny negatively charged subatomic particle moving around outside the nucleus |
| Energy Level | Any of the possible energies an electron may have |
| John Dalton | 1780's, proposed the Atomic Theory |
| Orbital | A region in an atom where there is a highprobability of finding electrons |
| Valence Electrons | An Electon in the outermost energy level of an atom |
| Number of protons | Number of Electrons or Atomic Number |
| Number of neutrons in an atom | Atomic Mass minus Atomic Number |
