Solutions/Answers to Exercises
Exercise 1. Explain why the electron affinity for nitrogen is zero when compared to C and O.
Electron configurations;
N: 1s22s22p3
O: 1s22s22p4
Carbon has 2 electrons in the 2p subshell and can accommodate another electron. Nitrogen has a half filled 2p subshell. Adding an electron would result in electron repulsion from an electron already occupying the orbital. The Eea of nitrogen would not be as favorable as with carbon. Oxygen has a more favorable Eea than N because of the increase in Zeff.
Exercise 2. Which of the following elements has the least favorable Eea? Which is most favored?
Exercise 3. The electron affinity of Cl is highly negative but the electron affinity of Ar is positive. Explain the difference using electron configurations.
Ar: [Ne]3s23p6
Cl has one orbital that can accommodate one more electron. An octet of electrons is very stable and energy would be released. Adding an electron to Ar would result in it being added to a 4s subshell which would require energy. Argon already has a full outer shell.