Question

What is the total contraction in atomic radius in going from Ce to Lu?

Answer 1

1. Moving from Ce to Lu, the atomic radius decreases due to lanthanide contraction.
2. This happens because the nuclear charge increases, but the added electrons enter the inner 4f orbitals, which do not shield well.
3. As a result, the effective nuclear charge felt by electrons increases, pulling the atom closer and reducing its size.
4. The total contraction in atomic radius from Ce to Lu is about 15 pm (picometers).
5. This contraction is seen clearly in the atomic radii data of lanthanides, although the decrease is not perfectly regular.

Thus, the total contraction in atomic radius from Ce to Lu is around 15 pm.