Does #I_3^(-)# exist?

1 Answer
Aug 4, 2017

Answer:

Does #I_3^(-)# exist.........?

Explanation:

Well, the answer is yes, and the Lewis structure distributes #3xx7+1=22# electrons.......

#[I-I-I]^-#, going from left to right, there are 7 electrons associated with the leftmost iodine, 3 lone-pairs, and 1 bonding electrons, hence this centre is neutral; the central iodine has 3 non-bonding lone-pairs, and 2 electrons from the #I-I# bonds, I.e. associated with EIGHT electrons, hence this centre is a formal anion; the rightmost iodine has the same electronic distribution as the leftmost, and this is a formally neutral centre.

Note that when you are next in the lab, try slurrying iodine in water (in which of course it is insoluble!). If you add a little iodide salt (say #KI#, if you can find it), the elemental iodine goes up into solution to form #I_3^(-)#, and other polyhalides......