Step 1: Use hydrogen atom energy relations.
Total energy of hydrogen atom:
\[
E_n = -\frac{13.6}{n^2} \, \text{eV}
\]
Potential energy is:
\[
U = 2E_n
\]
Step 2: Write expression for potential energy.
\[
U = -\frac{27.2}{n^2} \, \text{eV}
\]
Given:
\[
U = -1.088 \, \text{eV}
\]
Step 3: Equate values.
\[
\frac{27.2}{n^2} = 1.088
\]
Step 4: Solve for \(n^2\).
\[
n^2 = \frac{27.2}{1.088}
\]
\[
n^2 = 25
\]
Step 5: Find \(n\).
\[
n = 5
\]
Step 6: Final conclusion.
\[
\boxed{5}
\]