What type of electron is available to form bonds?

Valence electrons

Explanation:

The valence electrons are found in the outermost shell of an atom. They are the most loosely held electrons found within an atom. These valence electrons are involved and are used to form bonds when atoms combines together.

The energy required to remove these loosely held electrons is relatively low compared to electrons located in the inner orbitals. This is why when atoms combines, they use the outermost electrons to form bonds and mimic stable atoms like those of the noble gases.

a sonic boom is a loud boom that breaks the sound barrier

explanation: