Does anyone know the Lewis Structure for:

 

A. HOCN (HO-CN) Polar or Nonpolar?

B. COS Polar or Nonpolar?

You could easily look up the Lewis structures, but, surely you went over the Lewis structure rules in class? Try doing it by yourself first. If you have anything specific questions, then you should come back.

1. Look up Lewis structure on Wikipedia as suggested by ecoli.

 

2. To determine if something is polar, we first need to understand the concept of electronegativity. The most electronegative element is fluorine, this will try to draw electrons in a bond too itself no matter what it is bonded too. The next one we are interested in here is oxygen then nitrogen. Now, lets look at your first example.

 

We have HO-CN, lets split it into the two component groups: HO and CN. In the first group (HO) we have oxygen bonded too hydrogen so in this case we have a polar bond, the electrons are drawn towards the oxygen far more than the hydrogen. In the second group we also have a strongly electronegative element, nitrogen, boded too a far more electropositive element, carbon. This means that this bond is also polar.

 

We now know that both the groups are polar and from this we can pretty much say that HOCN is polar. To add too this we also have an oxygen bonded too the carbon here so we do indeed have a definite polar molecule

 

See if you can get the second one and if not we'll try to give more hints.