Question

14. A. What is the trend in atomic radii down a group?​

Answer 1

Answer:

This means that the valence electrons are down closer to the nucleus, decreasing the size of atom. Atomic radius increases down a group, because of the increases in the orbital sizes in successive principal quantum levels.

Answer 2

Atomic Radii

1) As you move down a group, atomic radius increases.

WHY? - The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase. [Image]

2) As you move across a period, atomic radius decreases.

WHY? - As you go across a period, electrons are added to the same energy level. At the same time, protons are being added to the nucleus. The concentration of more protons in the nucleus creates a "higher effective nuclear charge." In other words, there is a stronger force of attraction pulling the electrons closer to the nucleus resulting in a smaller atomic radius.