How many valence electrons are in #ICl_5#?

1 Answer
Nov 7, 2016

#"There are 42 valence electrons."#


Both iodine, and chlorine are halogens, and therefore each such atom has 7 electrons. In the Lewis structure, therefore, we have to distribute #6xx7# valence electrons, and therefore 21 valence electron pairs. The central iodine atom has a single lone pair, and each chlorine atom bears 3 lone pairs.

The geometry around iodine is square pyramidal. The electron pairs arrange themselves in an octahedral array, one of which is an iodine centred lone pair. And thus the symmetry descends from octahedral to square pyramidal.