| A | B |
|---|
| valence electrons | electrons at highest energy level and involved in bonding |
| electron dot diagram | a representation of valence electrons in an atom |
| chemical bond | The force that holds atoms together |
| symbol | One or two letters used to identify an element |
| atomic number | The number of protons in the nucleus of an atom |
| period | elements in the same row of the periodic table |
| group/family | Element in the same column of the periodic table |
| noble gas | an element in group 18; very unreactive |
| halogen | an element in group 17; most reactive nonmetal |
| alkali metal | an element in group ; most reactive metal |
