## Chemistry (7th Edition)

$a) Rb$ $b) N^{3-}$ $c) Cr^{3+}$
$a) Rb^{+}$is smaller because since it has lost an electron, there are more protons then electrons and thus the presence of more protons will pull the electrons closer, decreasing the atomic radius $b) N^{3-}$ is larger because it has more electrons than protons. This results in more shielding and more repulsion which increases the atomic radius. $c) Cr^{3+}$ is larger because it has lost fewer electrons than $Cr^{6+}$ Thus the shielding in $Cr^{3+}$ is larger than $Cr^{6+}$ and thus it has more repulsion and it is bigger