Question

`sp^3` hybridization - can somebody explain what my book is trying to say?

This is for `CH_4`. I understand that the electron configuration for `C` contradicts what actually happens in bonding, but I don't understand what #2 is trying to say.

Answer 1

All it is saying is that invoking hybridization, i.e. mixing of pure, differing atomic orbitals to form new, identical orbitals that are not rigidly `90^@` apart from each other, allows more flexibility in bonding.

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Recall that the four valence atomic orbitals (i.e. pure orbitals) of carbon are the `2s` and the `2p_x`, `2p_y`, and `2p_z`.

The `2s` is spherical, with no directionality, while the `2p` orbitals are each aligned along their coordinate axes. The `2p` orbitals DO have directionality, but only along their axes.

Since the `2p` orbitals are mutually orthogonal---that is, they are all `90^@` from each other, they cannot form bond angles other than `90^@`, and that is just not what is shown by experiment.

We did not observe

but we did observe

The pure `p` orbitals cannot rotate off their cartesian axes. If they did, they would not exist.