Answer
5.1 eV
Work Step by Step
Calculate the binding energy; It is the negative of the electrostatic potential energy. âkâ is the Coulomb constant, and "e" is the elementary charge.
Binding energy = -PE = $-k\frac{q_1q_2}{r}=-k\frac{(1.0e)(-1.0e)}{r}$
$$=k\frac{(1.60\times10^{-19}C)^2}{0.28\times10^{-9}m}=8.2\times10^{-19}J$$
This is about 5.1 eV.