The electron's initial energy is \( \boxed{-13.6 \, \text{eV}} \).
The electron's final energy is \( \boxed{-1.51 \, \text{eV}} \).
The energy of the photon is \( \boxed{1.94 \times 10^{-18} \, \text{J}} \).
\( \mathrm{h} = \boxed{6.626 \times 10^{-34} \, \text{s}} \).
\( \mathrm{f}_{\text{photon}} = \boxed{2.91 \times 10^{15} \, \text{s}^{-1}} \).\( \mathrm{c}_{\text{photon}} = \boxed{3.00 \times 10^{8} \, \text{m/s}} \).
\( \lambda_{\text{photon}} = \boxed{1.03 \times 10^{-6} \, \text{m}} \).