Question

"Atomic radius increases down a group because

A-more electrons are present at the same energy level.
B-proton number is increased.
C-electron energy shells are added.
D-There is no change down a group.

Answer 1

Atomic radius increases down a group in the periodic table due to the addition of energy shells and increasing electron shielding, resulting in larger principal quantum numbers and larger orbitals.

Step-by-step explanation:

The atomic radius increases down a group in the periodic table. This increase is attributed to the addition of electron energy shells as you move from one period to the next, meaning electron energy shells are added. As the principal quantum number gets larger with each successive element down a group, the valence electron shell lies further away from the nucleus, despite the increase in positive nuclear charge.

Another factor contributing to this trend is electron shielding, where inner shell electrons reduce the effective nuclear charge experienced by outer shell electrons. As a result, the increased shielding effect and larger orbitals as the principal quantum number increases to make the atomic radius larger down a group.