Question

What is single covalent bond and why does it form?

Answer 1

The result of a shared pair of valence electrons between two atoms. It contributes to the completion of the outer electron shell for each atom, giving a minimized molecular ground-state energy.

Explanation:

In general, the number and type of bonds possible with any element are determined by the valence electrons.

Those are the outermost electrons, which may be fairly evenly shared in primarily covalent bonds, or fairly unevenly shared in primarily ionic bonds.

It is worth noting that electronegativity differences between atoms determine the extent of the sharing and which atom "hogs" the electrons more, and not all molecules form entirely covalent or entirely ionic bonds.

"Missing" valence electrons are generally important, as they indicate orbitals that need to be completed through electron sharing or acquisition from another element. The "octet rule" should be applied to an element's valence electrons to see how many bonds it can form to "complete" its outer shell.