In the d-block, which electrons are considered valence electrons?

In the d-block, which electrons are considered valence electrons?

• A. s-shell electrons only
• B. d-shell electrons
• C. f-shell electrons
• D. core electrons

Answer: (B)

Valence electrons are the electrons that participate in bonding and determine how an element behaves in reactions. In the d-block, the outer region that can engage in chemistry is the d-sublevel, so the electrons in the d shell are the ones counted as valence electrons. This is why transition metals exhibit multiple oxidation states—the number of d-electrons that can be lost or shared changes during reactions. The f-shell belongs to the f-block and isn’t the valence focus for d-block chemistry, and core (inner) electrons do not participate in bonding. So the d-shell electrons are the valence electrons in the d-block.

Valence electrons are the electrons that participate in bonding and determine how an element behaves in reactions. In the d-block, the outer region that can engage in chemistry is the d-sublevel, so the electrons in the d shell are the ones counted as valence electrons. This is why transition metals exhibit multiple oxidation states—the number of d-electrons that can be lost or shared changes during reactions. The f-shell belongs to the f-block and isn’t the valence focus for d-block chemistry, and core (inner) electrons do not participate in bonding. So the d-shell electrons are the valence electrons in the d-block.