Question

Which of the following is a dipole?
KrF2, NH2Cl, CH2Br2, and SCN^-
I'm pretty sure that KrF2 and NH2Cl are not dipoles, but why? also, what makes something be a dipole?

Answer 1

If KrF2 is linear and symmetric, it is not a dipole. The others probably are. a molecule needs symmetry about a plane to avoid being a dipole. You can't always tell that from the chemical formula.

Answer 2

CH2Br2 is a molecule

Br-CH2-Br, linear almost, no dipole

SCN-

::S=C=N: triple bond between C,N

most definitely has dipole moment

Answer 3

I take the CH2Br2 back. It is a bent tetrahedral, so the Br side gives it a dipole moment.