Question

How do single covalent bonds form?

Answer 1

The direct overlap and sharing of electrons between two atoms of roughly equal electro negativity

Explanation:

An example is the formation of bonds in Methane. The Carbon atom hybridizes it four valance electrons into 4 equal `sp^3` bonds. The Hydrogen has 1 valance electron in a 1 s orbital.

The 1s hydrogen orbital overlaps with one of the 4 `sp^3` orbitals of the Carbon. The two atoms both share the electron density of the two electrons in the covalent bond formed by the overlap of the two original orbitals.

This new bond provides Hydrogen with the density of two electrons.
Hydrogen becomes stable with two electrons in its outer valance shell, similar to Helium.

By forming 4 covalent bonds with 4 hydrogens Carbon has access to the density of 8 electrons. Carbon with 8 electrons in its out valance shell becomes stable similarly to Neon.

The direct sharing of electron density by the overlap of electron orbitals allows atoms to achieve greater stability.