The radius of La3+ (atomic number of La = 57) is 1.06 Å. Which one of the following given values will be closest to the radius of Lu3+ (atomic number of Lu = 71)
Answer & explanation
Correct answer: option 3
The radius of \(La^{3+}\) is 1.06 Å. As we move down the lanthanide series, the atomic radii decrease due to the lanthanide contraction. This is because the lanthanide elements have a filled 4f subshell, which shields the outermost electrons from the nuclear charge less effectively than the 3d subshell in the transition metals.
As a result, the radius of \(Lu^{3+}\) is expected to be smaller than the radius of \(La^{3+}\). The closest answer is (3) 0.85 Å.