| A | B |
|---|
| alkali metals | soft, highly reactive metals; usually stored under oil; have 1 valence electron in the outermost "s" orbital (sublevel) |
| akaline-earth metals | reactive metals; have 2 valence electrons in the outermost "s" orbital (sublevel) |
| transition metals | a group of metals with various properties & various numbers of valence electrons; begin filling the "d" orbitals |
| inner transition metals | found at the bottom of the periodic table; begin filling the "f" orbitals |
| halogens | highly reactive nonmetals that combine with alkali metals to form salts; have 7 valence electrons |
| noble gases | inert, stable gases; have full outermost "s" and "p" orbitals |
| main-block elements | representative elements that have a wide range of chemical & physical properties |
| hydrogen | highly reactive element; most common element in the universe; behaves like no other element |
