# What are the group trends for atomic radius?

Jul 1, 2018

Across a period: $\downarrow$
Down a period: $\uparrow$

#### Explanation:

To be honest, the way I remember this is $\textcolor{\mathrm{da} r k b l u e}{\text{francium (Fr)}}$.

Fr has the $\textcolor{\mathrm{da} r k b l u e}{\text{largest}}$ atomic radius. Therefore, as you move farther from francium, the smaller your radius will be. If you move closer to francium, the larger your radius.

You can see Fr in the bottom left-hand corner. Therefore, if you move across any period from left to right, atomic radius will $\textcolor{\mathrm{da} r k b l u e}{\text{decrease}}$ because you're moving farther from Fr.

Going down a period will $\textcolor{\mathrm{da} r k b l u e}{\text{increase}}$ your atomic radius because you're moving closer to Fr.