Consider the molecules C2H2, CS2, SCl2, BrCl, CF4?

Question

11)
(a) Which has bonds that are most polar?
C2H2
CF4
SCl2
BrCl
CS2
(b) Which have a molecular dipole moment? (Select all that apply.)
CS2
BrCl
SCl2
CF4
C2H2

Answer 1

The most polar bond will be the one between atoms that have the biggest difference in electronegativity

F is the most electronegative element there is.
C has similar electonegativity to S.
Cl and Br are quite close to each other
So the biggest difference in electronegativity is between the C and F, thus the most polar bond is C-F in CF4

The molecular dipole moment depends on the sum of the dipole moments of all the bonds in each molecule.
CS2 is linear and the dipole moments are cancelling out each other so the total dipole moment is 0
Br-Cl has only one polar bond (Cl is more electronegative) so it has a dipole moment
SCl2 has 2 polar bonds and 2 lone pairs in the central atom (S). So the arrangement of the electron groups is tetrahedral and since there are only 2 bonds, there is a net dipole moment
CF4 the molecule is tetrahedral but has 4 identical polar bonds so the dipole moments cancel out each other and the molecule has no dipole moment
C2H2 is linear with the dipole moments of the polar C-H bonds canceling out each other (the molecule is H-Ctriple bondC-H) so the dipole moment is 0

Answer 2

Polarity Of Cs2

Answer 3

SCl2 because it has two unshared pairs of electrons and a bent shape.

b. SCl2, BrCl (different electronegitivities, but only slight)