Exercise $7\mathrm{.}5$ The electronic configuration $1s^{2}2s2p^3$ gives rise to $6$ terms: ${?}^{1}D,{?}^{3}D,{?}^{1}P,{?}^{3}P,{?}^{3}S,$ and ${?}^{5}S.$

a$)$ For each of the $6$ terms, give the level symbols associated with the term. What is the total number of distinct energy levels? Which of these levels is expected to have the lowest energy? Ans. $10$ levels; lowest is ${?}^5{S}_2.$

b$)$ Find the allowed transitions between each of the levels ${?}^3{P}_0,{?}^3{P}_1,$ and ${?}^3{P}_2$ of ground configuration $1s^{2}2s^{2}2p^2$ and the levels of part $($a$).$