Energy levels: $E_n = -13.6\,\text{eV}/n^2$ — introduced Ch 2, referenced throughout - Ground state wavefunction: $\psi_{100}(r) = \frac{1}{\sqrt{\pi}}\left(\frac{1}{a_0}\right)^{3/2} e^{-r/a_0}$ — introduced Ch 5 - Bohr radius $a_0 = 0.529\,\text{\AA}$ — introduced Ch 2