Periodicity

Periodic Table - What is a group? What is a period?
Families - How are elements grouped into families?
Metals - What % of elements do these make up?
Lanthanide Series (part of the inner transition metals) - Under "Meet the Family", what is unique about the actinide series?
Halogens - How many electrons do halogens have in their valence energy levels? What do halogens like to react with?
Inert gases (noble gases) - Why are they happy?