text: Iodine is not flamable or combustible. It does combine with O2 as an iodate. Iodine is not photosensitive but AgI is photosensitive. there are a number of isotopes.127 is the most common. The others are less massive, in general.(because the atomic mass is 126.9)\n\nSodium has a symbol of Na. Compounds have formulas, such as NaI, sodium iodide.