Moving from left to right across the Periodic Table, the atomic radii of the first row transition elements does not show the same trend as the s and p blocks, e.g. from lithium to fluorine. Why?

Question

Quizplus · Accepted Answer

In the s and p blocks, moving from left to right across the Periodic Table, atomic radii decrease due to an increase in nuclear charge (Zeff) and a constant number of energy levels (n). However, in the first row transition elements, the atomic radii do not decrease uniformly. This is because, in addition to the increase in Zeff, there is also an increase in electron-electron repulsion as the d orbitals are filled. The repulsion between the d electrons counteracts the effect of the increase in Zeff, leading to a smaller decrease in atomic radii compared to the s and p blocks. This is why option B is the correct choice.

Moving from Left to Right Across the Periodic Table, the Atomic