Verified answer

First of all find a table of electronegativity data, e.g.

http://home.c2i.net/astandne/help_htm/english/exam...

Then calculate the difference in electronegativity between each pair of atoms. If the difference is <0.5 the bond will be covalent and not significantly polar. If the difference is between 0.5 and 1.9 the bond will be covalent but increasingly polar. If the difference is greater than 1.9 the bond will be essentially ionic.

e.g. For S-Br

Si = 1.90; Br = 2.96; diff = 1.06, therefore Si-Br is polar covalent

For Li-O

Li = 0.98; O = 3.44; diff = 2.46, therefore Li-O is ionic

You should remember that there is no clear cutoff between these different bond types. The only absolute certainty is that if the electronegativity difference is zero, i.e. the atoms are the same, the bond is nonpolar covalent. The figures of 0.5 and 1.9 are just guidelines for classification

C-P is non-polar covalent

I mean just saying

Si - Br polar covalent

Li - F ionic

Br- F polar covalent

Br- Br non polar covalent

N - P polar covalent

C - P polar covalent

Si - O polar covalent

K - Cl ionic

S - F polar covalent

P - Br polar covalent

Li - O ionic

N - P polar covalent