What is Iodine?
[[File:Iod kristall.jpg|thumb|A large iodine crystal]] '''Iodine''' is a [[chemical element]]. Its [[atomic number]] (which is the number of [[Proton|protons]] in it) is 53, and its [[atomic mass]] (the number of protons plus [[neutron|neutrons]]) is 127. It is part of the Group 7 ([[halogen]]s) on the [[periodic table|periodic table of elements]] and its electronic configuration is 2,8,8,18,17.<ref name=coolfact>{{cite web|url=http://www.chemicool.com/elements/iodine.html|publisher=Chemicool|title=Iodine Element Facts|access-date=2011-03-16}}</ref> It is a [[nonmetal]]. ==Properties== ===Physical properties=== [[File:IodoAtomico.JPG|thumb|Iodine vapor]] Iodine is a dark violet-gray-black<ref>{{Cite web|title=PharmaWiki - Iod|url=https://www.pharmawiki.ch/wiki/index.php?wiki=Iod|access-date=2024-08-29|website=www.pharmawiki.ch}}</ref> solid. It is also a [[nonmetal]] and a [[halogen]]. It sublimes when heated to make a bright purple vapor. This vapor is very irritating, although colorful. Iodine does not dissolve in water, but it does dissolve in a [[Solution (chemistry)|solution]] of an [[iodide]] in water. It dissolves easily in [[organic chemistry|organic]] [[solvent]]s. ===Chemical properties=== Iodine is at the bottom of the halogens and is the least [[chemical reaction|reactive]] of the halogens. Iodine is an [[oxidizing agent]], though not as strong as [[fluorine]] or [[bromine]] or [[chlorine]]. It can become the colorless iodide ion if another atom or molecule gives an iodine atom one of its electrons. This is called reduction. Iodine reacts with [[hydrogen sulfide]] or [[hydrazine]] to make [[Hydrogen iodide|hydriodic acid]]. Iodine dissolves in [[oleum]] to make a bright blue solution of I<sub>2</sub><sup>+</sup> and [[sulfur dioxide]]. This [[cation]] is also made when iodine reacts with [[antimony pentafluoride]]. Iodine reacts with [[base (chemistry)|bases]] to make [[hypoiodite]] and [[iodide]]. The hypoiodite [[disproportionation|disproportionates]] to [[iodate]] and [[iodide]]. Iodine reacts