Physical Chemistry , 1st ed.

12.14 Summary 415

2 p

2 s

2 p

2 s

NONO

1 s

2 p

HFHF

2 s

Figure 12.24 Molecular orbitals of the heteronuclear diatomic molecules NO and HF. The en-

ergy axis is not to scale, and only the valence shell electrons are shown. Compare these diagrams

with those in Figure 12.23.

Our understanding of molecular quantum mechanics begins with mole-

cular orbitals, which are based on atomic orbitals. As with many tools used

to describe nature, we started at the bottom and are working our way up.

The fundamentals of molecular quantum mechanics provide us with the

tools to understand most of matter, at least as we understand it today. The

next few chapters broaden the applications of quantum mechanics to mo-

lecular systems.