Which part of the atom is responsible for chemical bonding

That would be the electron, because of the Octet Rule, electrons in an atom want to become stable by gaining, losing, or sharing electrons with other atoms until they have 8 valance electrons. Because of this, in a chemical bond atoms share electrons with eachother so noth can have 8 valance electrons and both can become stable.

Aneutral atom must have the same number of neutrons and protons? no, they must have the same number of protons and electrons