| A | B |
|---|
| nucleus | atom's center |
| proton | positive-charged atom particle |
| neutron | neutral-charged atom particle |
| valence | number of electrons in outer energy level |
| dot diagram | element symbol and valence electron number |
| atomic number | number of protons |
| group | element family |
| period | row across periodic table |
| halogen | family with valence of seven |
| ion | charged atom |
| ionic bond | compound formed by transferred electrons |
| polyatomic ion | charged compound |
| crystal | solid 3-d pattern of ions or atoms |
| covalent bond | formed by sharing electrons |
| double bond | sharing 2 pairs of electrons |
| polar | bond of unequally shared electrons |
| nonpolar | bond of equally shared electrons |
| oxidation number | number of electrons gained, lost, or shared during bond formation |
| electron | negative-charged atom particle |
