Answer
-0.7 eV
Work Step by Step
The answer to Problem 1 is 5.1 eV (to 2 significant figures), without counting the contribution to the binding energy from the electron clouds. The actual binding energy is less, 4.43 eV. The contribution of the electron clouds to the binding energy is 4.43eV – 5.1eV = -0.7 eV.
It is negative because the electron repulsion makes the opposite-charge ions easier to separate.