Energy of the state in units of the hydrogen atom ground state energy is — Atomic Structure Chemistry Question

💡 Solution & Explanation

The energy of a hydrogen-like ion is $E = E_H \frac{Z^2}{n^2}$, where $E_H$ is the ground state energy of hydrogen. For Li$^{2+}$ ($Z=3$) in state $S_1$ ($n=2$), $E = E_H \frac{3^2}{2^2} = E_H \frac{9}{4} = 2.25 E_H$. Therefore, correct answer is C.