Question

What is the reason for atomic orbitals to form hybrid orbitals in a chemical bond? What causes them to do so?

Answer 1

Hybridization is a mathematical concept developed to cope up the flaws of Valence Bond theory. It hinges solely on the linear combination of wave functions of atomic orbitals having more or less the same energy. Hybridized state is a purely theoretical concept and cannot be detected even spectroscopically.

There is nothing like "collapse." The wave function of a hybridized orbital is "mixing" of the atomic orbitals only. The number of hybrid orbitals is same as the number of atomic orbitals participating in the "mixing up". The wave functions interfere constructively or destructively to give rise to equivalent orbitals known as hybrid orbitals.