As you move down a group, the number of electrons means that the atomic radius of the atom

As you move down a group in the periodic table, the number of electrons increases. This is because each subsequent element in a group has an additional energy level or shell of electrons.

Here are the steps that explain why the atomic radius increases as you move down a group:

1. Each subsequent element in a group has an additional energy level or shell of electrons. This means that the number of electrons increases as you move down a group.

2. These additional electrons are located further from the nucleus because they occupy higher energy levels.

3. The increased distance between the nucleus and the outermost electrons results in a larger atomic radius.

4. Additionally, the effect of electron shielding also contributes to the increase in atomic radius. As more electron shells are added, the inner shells of electrons shield the outermost electrons from the positive charge of the nucleus. This reduces the attractive force between the nucleus and the outermost electrons, allowing the outermost electrons to move further away from the nucleus, which increases the atomic radius.

So, as you move down a group in the periodic table, the increase in the number of electrons and the effect of electron shielding result in a larger atomic radius.