What are the expected bond angles of ICl4+? Choose all that apply:
a) 90 degrees
b) 109.5 degrees
c) 120 degrees
d) 180 degrees
Answer: A, C, D.
Explanation
It has a see-saw shape and thus will have bond angles of 90, 120 and 180. Thus A, C, D.
The polyatomic ion has seven valence electrons for each atom, subtracting the electron lost (indicated by the +1 charge on the ion). As a result, the Lewis diagram will show a total of 34 electrons (an octet for each chlorine as well as a lone pair and four single bonds on the iodine, giving it a steric
Trigonal bipyramidal structures are the most likely for species with a steric number of five at their center atom. The lone pair is usually positioned as close to the central atom as possible, but these rules may not apply to all types of molecules.
The structure would be a square-based pyramid if the lone pair is in an axial location. The single pair has a 180-degree angle with one chlorine and ninety-degree angles with the three equatorial chlorines. Stable structures require lone pairs to be as far away from other electrons as possible. Three 90° angles are not ideal.
If the lone pair is in an equatorial location, it will have 90-degree angles with the two chlorines that are in axial positions and 120-degree angles with the two chlorines that are in equatorial positions. That’s ideal. (Turns out that 180-degrees isn’t much better than 120-degrees, but
As a result, the predicted structure is a “seesaw.”
