Extra electrons

[Kaylin Krahn 1I]

In 3.61 for example, how do you know where to put the extra electrons? Iodine gets more lone pairs added instead of bonding more. Do you just try different structures and test for the lowest formal charge?

[Dylan Davisson 2B]

You know that the Lewis structure looks the way it does for the Iodine Dichloride anion (2 bonding pairs and 2 lone pairs on I) not only because it is the configuration in which the most atoms have a formal charge of 0 (both Cl atoms have formal charge of 0), but also because if any double bonds are used, the charge of the anion will not be +1, but will be of a higher positive charge. This means that the Lewis structure would not properly reflect the Iodine Dichloride anion, so the only possible way to present it is with single bonds.