Which groups correspond to non-representative elements, the transition metals?

• A. Groups 1A-8A
• B. Groups 1B-2B
• C. Groups 3-12
• D. Lanthanide and Actinide series

Answer: (B)

Non-representative elements are not in the main s- and p-blocks of the periodic table. The transition metals occupy the central d-block, the part of the table between the alkaline earth metals and the main-group p-block elements. Their defining feature is partially filled d orbitals, which gives them variable oxidation states, versatile chemistry, and typical metallic properties. The lanthanide and actinide series are the inner transition metals tucked below; they’re also non-representative but belong to a different block (the f-block) than the main transition-metal groups. So, the groups that correspond to the transition metals are the central d-block elements.