Skip to content
ScienceQuest

Tetrachloroiodate ion (ICl₄⁻) Lewis structure

36 valence electrons, square planar, a charge of −1

I Cl Cl Cl Cl − −
ICl₄⁻ as the Lewis Structure Generator draws it: lone pairs as dots, nonzero formal charges circled.

Build ICl₄⁻ step by step in the Lewis Structure Generator

What is the Lewis structure of ICl₄⁻?

Tetrachloroiodate ion, ICl₄⁻, has 36 valence electrons. Iodine is the central atom, joined by four I−Cl single bonds. It carries two lone pairs on the central I and three on each Cl. Its only formal charge is −1, on the central I. I is AX₄E₂: square planar, with ideal bond angles of 90° and 180°.

Valence electrons in ICl₄⁻

Element Group Valence electrons Atoms Electrons
Iodine 17 7 1 7
Chlorine 17 7 4 28
Charge of 1− +1
Total 36

In one line: 7 + 4 × 7 + 1 = 36. Each atom brings the valence electrons its group gives it, and the negative charge adds one electron for each unit.

How to draw the ICl₄⁻ Lewis structure

  1. Count the valence electrons. Valence electrons: I 7 and each Cl 7, and the 1− charge adds 1. 7 + 4 × 7 + 1 = 36.
  2. Choose the central atom. I goes in the middle: I is the least electronegative atom other than H, χ 2.66 against 3.16 for Cl.
  3. Join the atoms with single bonds. Four single bonds use 8 electrons, leaving 36 − 8 = 28.
  4. Complete the outer atoms. Each outer atom takes enough lone pairs to reach eight: 4 Cl × 6 = 24, leaving 28 − 24 = 4.
  5. Put the rest on the central atom. The 4 left go on the central atom as two lone pairs on I, and I now has 12 electrons round it. That is more than eight, which an atom from period 3 on can hold.
  6. Make multiple bonds where needed. Every atom already has an octet or more, so no lone pair needs to become a bond.

Lone pairs and formal charges in ICl₄⁻

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
I (central) 1 four single bonds 2 12 7 − 4 − 4 = −1
Cl 4 one single bond 3 8 7 − 6 − 1 = 0

V is the atom’s valence electrons, N its nonbonding electrons and B its bonding electrons. The formal charges add up to −1, the charge on the ion.

Shape and polarity of ICl₄⁻

Central atom I
VSEPR class AX₄E₂
Electron geometry octahedral
Molecular geometry square planar
Ideal bond angles 90° and 180°
Polarity, an estimate not applicable

An ion carries a net charge, so whether its bond dipoles cancel is not the question polarity asks.

I has four σ bonds and two lone pairs, six electron domains in all, so its electron geometry is octahedral. Counting only the bonded atoms, the molecular geometry is square planar.

The VSEPR Molecular Geometry viewer turns the AX₄E₂ shape in 3D, lone pairs included.

Work with ICl₄⁻