Iodine (I) is used to seed clouds, detect and treat cancer, prevent infections, and protect people from radiation in the even of a nuclear accident. Most of the iodine found in nature is in seaweed. Pure iodine can also be obtained from natural brines. This book delves into the properties of the group 17 elements, also called the halogens, and the subatomic makeup of iodine. Readers discover the role of valence electrons, and the use of iodine in biology labs and in identifying types of bacteria. Iodine compounds are examined and their many uses explained. The book also includes a discussion of iodine deficiency around the world.