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Lewis structure

Lewis structure of SOCl₂

26 valence electrons. One S=O double bond and two S-Cl single bonds, with one lone pair on S, so S has 10 electrons around it (an expanded octet).

ClClSO
  • S
  • O
  • Cl
  • lone pair

SOCl₂Thionyl chloride

Trigonal pyramidal

AB₃E: 3 bond pairs, 1 lone pair

  • Hybridisationsp³
  • Bond angleless than 109.5°
  • Polaritypolar

Lewis structure

26 valence electrons
SOClCl

Formal charges: none

Why this shape

  1. S has 6 valence electrons. It uses four in one double bond to O and two single bonds to Cl, so two are left as one lone pair.
  2. Steric number = three sigma bonds + one lone pair = 4, so S is sp³ hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
  3. Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With one lone pair in place of atoms, the atoms make a trigonal pyramidal shape.
  4. Repulsion falls in the order lone pair to lone pair > lone pair to bond pair > bond pair to bond pair. The lone pair pushes the bond pairs closer, so the angle is less than 109.5°, less than the ideal 109.5°.
  5. The bond dipoles do not cancel in the trigonal pyramidal shape, so SOCl₂ is polar.
Working

How to draw it

  1. Count the valence electrons: S 6 + O 6 + 2 × Cl 7 = 26 valence electrons, 13 pairs.
  2. Put S in the middle and join it to the three 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. Where an atom is still short of an octet, turn a lone pair of its neighbour into a shared pair: that makes a double or triple bond.
  5. Result: one S=O double bond and two S-Cl single bonds, with one lone pair on S, so S has 10 electrons around it (an expanded octet).
  6. Formal charge = valence electrons − lone pair electrons − number of bonds. Here: none.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Lewis structure of SOCl2: quick answers

How many valence electrons are in SOCl2?

S 6 + O 6 + 2 × Cl 7 = 26 valence electrons, 13 pairs.

What are the formal charges in the Lewis structure of SOCl2?

Every atom has a formal charge of zero.

How many lone pairs are in the Lewis structure of SOCl2?

9 in all, 1 of them on the central S.

Try any molecule