Question

The atomic and ionic radii ($M^{3+}$ ions) of Lanthanide elements decrease with increase in atomic number. This effect is called as:

• A. Lanthanoid contraction
• B. Lanthanoid expansion
• C. Actinoid contraction
• D. none of these

Answer 1

The correct option is A Lanthanoid contraction

The atomic and ionic radii ($M^{3+}$ ions) of Lanthanide elements decrease with increase in atomic number.

This effect is called Lanthanoid contraction. This is due to poor shielding of f electrons.