Give the trend for atomic radius across a period and down a group, and explain each of these trends in terms of attraction, repulsion, and effective nuclear charge.

Atomic radius decreases across a period due to increase in attraction between nucleus & electrons in the valence shell, thus increasing effective nucleus charge.

Atomic radius increases down the group due to addition of one shell at each successive step

Hope this helps!

What do you need with it’s not a question your just stating what it says

C, small, hard spheres with insignificant volumes