Question

Why is there an increase in the atomic radius of transition elements at the end of the period?

(a) Increased electron-electron repulsions

(b) Decreased electron-electron repulsions

(c) Increase in nuclear charge

(d) Increase in atomic mass

This question was posed to me during an online interview.

My question is taken from General Properties of the Transition Elements (D-Block) topic in division D and F-Block Elements of Chemistry – Class 12

Answer 1

Right choice is (a) Increased electron-electron repulsions

For explanation: Near the end of the period, the increased electron-electron repulsions between added electrons in the same orbitals are greater than the attractive forces due to increased nuclear charge. This results in the expansion of the electron cloud and therefore, increases the atomic size.