Valence is defined as the bonding capacity of an atom, usually equal to the number of unpaired electrons required to complete the outermost shell.

Valence is defined as the bonding capacity of an atom, usually equal to the number of unpaired electrons required to complete the outermost shell.

• A. The energy level of the highest occupied shell.
• B. The bonding capacity, usually equal to the number of unpaired electrons required to complete the outer shell.
• C. The nucleus charge.
• D. The number of protons.

Answer: (B)

Valence is about how many bonds an atom can form, tied to how its outer shell can be completed. In most cases, the bonding capacity matches the number of electrons needed to fill the outermost shell, which is effectively the number of unpaired electrons that must be involved in bonding to achieve a full valence shell. So the statement that valence is the bonding capacity of an atom, usually equal to the number of unpaired electrons required to complete the outer shell, correctly describes the concept. The other ideas don’t describe valence: the energy level of the highest occupied shell is about energy placement, not bonding potential; the nucleus charge and the number of protons refer to the atomic number, which determines identity and some properties, but not how many bonds the atom forms.

Valence is about how many bonds an atom can form, tied to how its outer shell can be completed. In most cases, the bonding capacity matches the number of electrons needed to fill the outermost shell, which is effectively the number of unpaired electrons that must be involved in bonding to achieve a full valence shell. So the statement that valence is the bonding capacity of an atom, usually equal to the number of unpaired electrons required to complete the outer shell, correctly describes the concept.

The other ideas don’t describe valence: the energy level of the highest occupied shell is about energy placement, not bonding potential; the nucleus charge and the number of protons refer to the atomic number, which determines identity and some properties, but not how many bonds the atom forms.