Question

When forming a chemical bond only the ________ electrons participate in the bonding process.

Answer 1

The outer shell electrons are only involved in the bonding process since they are the only 'incomplete' shell and it needs to be fulfilled by another element. 

Answer 2

Answer: When forming a chemical bond, outer shell electrons participate in the bonding process.

Explanation:

A chemical bond is defined as the bond which is formed by the combination of atoms or ions.

There are two types of chemical bonds:

• Ionic bonds: They are defined as the bonds which are formed by the complete transfer of valence (outer shell) electrons from cation (positively charged ions) to anion (negatively charged ions). For Example: NaCl, $BaSO_4$ etc...
• Covalent bonds: They are defined as the bonds which are formed by the sharing of valence electrons between the atoms. For Example: HCl, $CH_4$ etc..

Inner shell electrons are the electrons which are tightly held by the electrons. They are called as core electrons.

Outer shell electrons are the electrons which are not tightly held by the electrons. They are called as valence electrons.

Hence, when forming a chemical bond, outer shell electrons participate in the bonding process.