Valence electrons are electrons in which part of the atom?

• A. Electrons in inner shells
• B. Electrons in the outermost shell
• C. Protons in nucleus
• D. Neutrons

Answer: (B)

Valence electrons are the electrons in the outermost energy level of an atom. They are the ones that participate in chemical bonding because they are the most loosely held by the nucleus and can be gained, lost, or shared when atoms interact. The inner-shell electrons stay close to the nucleus and generally don’t take part in bonding, so they’re called core electrons. Protons and neutrons reside in the nucleus, not as electrons, so they aren’t valence electrons. This outermost set of electrons largely determines an element’s reactivity and bonding behavior. For example, sodium has one valence electron that it tends to lose to form bonds, while chlorine has seven valence electrons and tends to gain one to complete its outer shell.