Step 1: Energy Levels in the Hydrogen Atom
The energy of an electron in the \( n^{th} \) orbit is:
\[
E_n = \frac{-13.6}{n^2} { eV}
\]
For \( n = 1 \):
\[
E_1 = -13.6 { eV}
\]
For \( n = 2 \):
\[
E_2 = \frac{-13.6}{4} = -3.4 { eV}
\]
Step 2: Calculating Excitation Energy
\[
E_{{excitation}} = E_2 - E_1
\]
\[
= (-3.4) - (-13.6)
\]
\[
= 10.2 { eV}
\]
The excitation energy is \( 10.2 \) eV.