Numford
Lewis structure

Lewis structure of ICl₂⁻

22 valence electrons. Two I-Cl single bonds, with three lone pairs on I, so I has 10 electrons around it (an expanded octet).

ClICl
  • I
  • Cl
  • lone pair

ICl₂⁻Dichloroiodate ion

Linear

AB₂E₃: 2 bond pairs, 3 lone pairs

  • Hybridisationsp³d
  • Bond angle180°
  • Polarityion, charge −1

Lewis structure

22 valence electrons
IClCl−

Formal charges: I −1

Why this shape

  1. I has 7 valence electrons. In the Lewis structure it makes two single bonds to Cl and keeps three lone pairs, which leaves it a formal charge of −1.
  2. Steric number = two sigma bonds + three lone pairs = 5, so I is sp³d hybridised.
  3. Five electron pairs point to the corners of a trigonal bipyramid (trigonal bipyramidal electron geometry). With three lone pairs in place of atoms, the atoms make a linear shape.
  4. All three lone pairs take the equatorial positions, 120 degrees apart, and the two bonds point up and down.
  5. The lone pairs balance each other, so the bonds are not pushed out of place and the angle stays at 180°.
  6. ICl₂⁻ is an ion with an overall charge of −1, so it is not described as polar or non-polar.
Working

How to draw it

  1. Count the valence electrons: I 7 + 2 × Cl 7 + 1 for the ⁻ charge = 22 valence electrons, 11 pairs.
  2. Put I in the middle and join it to the two outer atoms with single bonds.
  3. Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
  4. Result: two I-Cl single bonds, with three lone pairs on I, so I has 10 electrons around it (an expanded octet).
  5. Formal charge = valence electrons − lone pair electrons − number of bonds. Here: I −1.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Lewis structure of ICl2-: quick answers

How many valence electrons are in ICl2-?

I 7 + 2 × Cl 7 + 1 for the ⁻ charge = 22 valence electrons, 11 pairs.

What are the formal charges in the Lewis structure of ICl2-?

I −1; every other atom is zero. Formal charge = valence electrons - lone pair electrons - number of bonds.

How many lone pairs are in the Lewis structure of ICl2-?

9 in all, 3 of them on the central I.

Try any molecule