Which molecules are polar/non-polar?
Expect non polar in: Homonuclear diatomic molecules eg H2 and in addition: Linear molecules eg CO2 Symmetric disk shaped molecules trigonal planar, square planar eg. BF3, XeF4 Symmetric ball shaped molecules such as tetrahedral and octahedral eg CF4 and SF6 The above apply in case of symmetrical substitution about the central atom eg CF4 is non polar but CH3F and CH2F2 and CHF3 are polar. Expect polar molecules in: V shaped (angular) molecules eg CF2 T shaped molecules eg ClF3 See-saw molecules eg SF4 Pyramidal molecules such as trigonal pyramidal or square pyramidal eg NF3, BrF5 Note: ClF3 and SF4 has to move in the polar molecules.
