4f24 \mathrm{f}^{2}4f2
4f16 s24 \mathrm{f}^{\mathrm{1}} 6 \mathrm{~s}^{2}4f16 s2
5d16s25 d^{1} 6 s^{2}5d16s2
6s26p16 s^{2} 6 p^{1}6s26p1