Iodine (I) is chemical element number 53 and is a halogen in group 17. Iodine-127 is the non-radioactive element that refers to the one on the Periodic Table. Iodine-127 has 53 protons, 74 neutrons, and 53 electrons. Iodine was also once thought to undergo sublimation, but it just has a very short liquid state before being turned into a bright purple gas. It is used in the body to prevent your throat from being too big. It's symbol is I.