Question

When observing/measuring the structures (abxey) in part b of the procedure, were you able to confirm that lone pair orbitals require more space than bonding pair orbitals? In the structures with five domains, which position did the bigger balloons (lone pairs) prefer, axial or equatorial?

Answer 1

Lone pairs require more space than bonding pairs and prefer equatorial positions in structures with five domains to minimize repulsions, making the molecule more stable.

Step-by-step explanation:

In the context of molecular geometry and VSEPR theory, lone pair orbitals (lone pairs) indeed require more space than bonding pair orbitals, which has an impact on the shapes of molecules.

When considering structures with five domains, such as those exemplified by SF4, a molecule with the formula designation AX4E indicates one lone pair (E) and four bonding pairs (AX4). In trigonal bipyramidal arrangements, lone pairs prefer the equatorial positions rather than axial ones. This is because equatorial positions lead to fewer close 90-degree LP-BP (lone pair-bonding pair) repulsions compared to axial positions.

As an example, if a lone pair is placed in an axial position on SF4, there will be three 90-degree LP-BP repulsions, whereas if it is placed in an equatorial position, there will only be two such repulsions, resulting in a more stable configuration.