Question 1
Which reaction, below, represents the electron affinity of Li?
a. Li(g) –> Li + (g) + e
b. Li + (g) + e –> Li(g)
c. Li(g) + e –> Li – (g)
d. Li – (g) –> Li(g) + e
Question 2
Explain why the electron affinity of nitrogen is lower (less negative) than those of both carbon and oxygen.
Question 3
Answer to question 1
Answer: c
Li(g)+e−→Li−(g)Li(g)+e−→Li(g)−
The enthalpy change of this reaction is -59.6kJ/mol. Hence, it is exothermic.
Answer to question 2
The atomic number of nitrogen is seven. Nitrogen has a half-filled p orbital. The number of electrons in the p orbital in nitrogen is three. Nitrogen, therefore, does not accept more electrons as it has a stable configuration. It needs energy if nitrogen wants to add more electrons.
The atomic number of carbon is six, and the atomic number of oxygen is 8. Both carbon and oxygen do not have half-filled p orbital. The number of p electrons in carbon and oxygen is two and four, respectively.
Therefore, nitrogen has a lower electron affinity than carbon and oxygen.
Answer to question 3
