Vial's Periodical Periodicals: Iodine (53)

Iodine
Atomic Number: 53
Atomic Weight: 126.9
Element Group:  Halogens
Phase at Room Temperature: Solid

I may be a dull gray solid at room temperature, but if you heat me up just a little bit, I will sublimate into a fantastic purple vapor. (Sublimation is when a solid goes strait from solid to gas without first melting into a liquid.)

Your body (assuming you're a human) uses small amounts of me to help develop itself mentally and physically.  Without me, the babies of pregnant women can develop physical disabilities and mental diseases. That's why I'm added to salt. 

Another interesting aspect of my chemical makeup is my reaction with starch. When I come in contact with it I turn a deep blue.