Question

What are the favored geometrical arrangements for ABn molecules for which A atom has 2,3,4,5 and 6 pairs of electrons in its valence shell

Answer 1

2 is linear. 3 is trigonal. 4 is tetrahedral. 5 is trigonal bipyramidal. And 6 is octahedral.

2 - linear AB

2 electron domains: 2 bonding, 0 nonbonding; s,p atomic orbital set, two sp hybrid orbital set, 180-degrees (CO₂).

3- Trigonal planar (or) planar AB3

3 electron domains: 3 bonding, 0 nonbonding; s,p,p atomic orbital set, three sp2 hybrid orbital set (BF₃).

4- Tetrahedral AB4

4 electron domains: 4 bonding, 0 nonbonding; s,p,p,p atomic orbital set, four sp3 hybrid orbital set (CH₄).

5 - Trigonalbipyramidal AB5

5 electron domains: 5 bonding, 0 nonbonding; s,p,p,p,d atomic orbital set, five sp3d hybrid orbital set (PCl₅).

6 - Octahedral AB6

6 electron domains: 6 bonding, 0 nonbonding; s,p,p,p,d,d atomic orbital set, six sp3d2 hybrid orbital set (SF₆).