1. Draw an orbital overlap diagram to represent the bonding in ammonia, NH3.

2. Draw the Lewis structure and structural formula for:

a) HCN

b) SO32-

3. Experimental evidence suggests that the nitrogen atom in ammonia, NH3, has four identical orbitals in the shape of a pyramid or tetrahedron.

a) Draw an energy-level diagram to show the formation of these hybrid orbitals. (Hint: No electron promotion is required.)

b) Name the type of hybrid orbitals found in NH3. Of the four hybrid orbitals on the N atom, how many will take part in bonding? Explain.

c) Draw for yourself the energy-level diagram showing the hybrid orbitals formed in the C atom when it bonds. Now look at those hybrid orbitals and those of the N atom, and describe how the bonding with a N atom will differ with the bonding that occurs with a C atom, even though both atoms have four hybrid orbitals oriented in a tetrahedral shape.

4. a)   Calculate the differences in electronegativity between the elements in each of these compounds.

i) CaBr2

ii)  Na3N

iii) CH4

b) Predict whether each of these compounds would be an ionic or a molecular compound and justify each prediction.

c) Rank the bonds in these compounds in order of decreasing ionic character. Where do we always find compounds containing metals, in this ranking order?