Question

How do the atomic radii of transition elements vary across a particular series?

Answer 1

1. Atomic radii generally decrease with increasing atomic number in a series, but the decrease slows down midway.
2. An initial decrease happens due to the increasing nuclear charge pulling electrons closer.
3. Added electrons enter (n − 1)d subshell, increasing shielding that counterbalances the nuclear charge later.
4. Near the end of the series, atomic radii slightly increase due to electron-electron repulsions outweighing nuclear attraction.
5. From Mn to Ni, radii remain nearly constant as repulsions and attraction balance out.
6. Moving down a group, atomic radii increase due to added electron shells.
7. Radii of the second and third transition series elements are similar because of lanthanoid contraction.