Question

How are the transition elements classified?

Answer 1

1. They belong to the d-block of the periodic table, where electrons enter the (n − 1)d subshell.
2. They are placed between the s-block and the p-block elements, showing transitional behavior.
3. They are classified into four transition series based on which (n − 1)d subshell fills:
   1. First series (3d): Sc (21) to Zn (30)
   2. Second series (4d): Y (39) to Cd (48)
   3. Third series (5d): La (57), Hf (72) to Hg (80)
   4. Fourth series (6d): Ac (89) and elements with Z ≥ 104
4. Transition elements have an electronic configuration of type `(n- 1)d^(1 - 10) ns^(1 - 2)`.