For $2s_{1/2}$ ($l = 0$, $j = 1/2$):

Relativistic: $-1.47 \times 10^{-4}$ eV - Spin-orbit: $0$ eV (because $l = 0$) - Darwin: $+2.26 \times 10^{-5}$ eV - **Total: $-1.24 \times 10^{-4}$ eV**