Question

Atomic size of gold is almost the same as that of silver due to:

• A. Almost the same electropositive character of two metals
• B. The transition metals contraction in a series
• C. The effect of lanthanide contraction
• D. The same crystal structure of silver and gold

Answer 1

The correct option is C The effect of lanthanide contraction

Atomic size of gold is almost the same as that of silver because of lanthanide contraction effect.
When we move from La to Lu (i.e. Lanthanide series) the size of atoms decreases more than expected due to the poor shielding effect of f- orbitals. This phenomenon is known as Lanthanide contraction.
As a result of lanthanide contraction, the atomic radii of the 4d and 5d elements are quite similar from group 4.