Why is #SCl_2# polar?

I have the Lewis structure and from there I can see that it has polar bonds because of the Cl, so both S - Cl bonds are polar bonds. But shouldn't the bonds cancel each other out?

1 Answer
Apr 19, 2017

Answer:

Because of the lone pairs of electrons present on the sulfur atom.

Explanation:

The Lewis structure for sulfur dichloride should show that two lone pairs of electrons are present on the sulfur atom.

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These lone pairs of electrons are responsible for giving the molecule a bent molecular geometry, much like the two lone pairs of electrons present on the oxygen atom are responsible for giving the water molecule a bent geometry.

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Consequently, the two dipole moments that arise from the difference in electronegativity that exists between the sulfur and the two chlorine atoms will not cancel each other out.

The #"S"-"Cl"# bond is polar because the difference in electronegativity between the two atoms is # > 0.5#, but the resulting dipole moments will not cancel each other out because the molecule is not symmetrical.

So remember, the polarity of a molecule depends on two things

  • the polarity of the bonds #-># you must have polar bonds in order to be able to talk about a polar molecule
  • the shape of the molecule #-># symmetrical molecules are nonpolar regardless if they have polar bonds or not

Therefore, you can say that a polar molecule must

  • have polar bonds
  • be assymetrical