Q10.31P - Chemistry: Molecular Nature Of Matter And Change

Question

Consider the following molecular shapes.

a.Which has the most electron pairs (both bonding and lone pairs) around the central atom?

b.Which has the most lone pairs around the central atom?

c.Do any have only bonding pairs around the central atom? A B C

Step-by-Step Solution

Answer

a) Molecules A has the greatest number of electron pairs, both bonding and lone pairs, around the central metal atom.

b) Molecules A and B have the greatest number of lone pairsaround the central metal atom.

c) Molecules C and D have bonding pairs, around the central metal atom. 

Step 1: Molecule A

The geometry of molecule A is square planar which results when there are 4 bonds and 2 lone pairs on the central atom. Molecule A has 4 bond pairs and 2 lone pairs around the central atom.

Step 2: Molecule Aand molecule B

Molecules A and B have 2 and 1 lone pairs respectively.   Molecule B is a see-saw-shaped structure thatforms when a lone pair is present on the central atom in a trigonal pyramidal geometry.  

Step 3: MoleculesC and D

The geometry of molecule C is trigonal bipyramidal which has 5 bonding pairs around the central atom and there is no lone pair present. Similarly, the geometry of molecule D is tetrahedral which has 4 bonding pairs and no lone pair around the central atom. So, 

Molecules C and D have 5 and 4 bonding pairs respectively.