How would you explain why the electron affinity of nitrogen is lower (less negative) than those of both carbon and oxygen?

Electron affinity refers to the energy change that occurs when an electron is added to a neutral atom to form a negative ion (anion). In the case of nitrogen, carbon, and oxygen, they are all nonmetals and are located in the same period (second period) of the periodic table.

Nitrogen (N), carbon (C), and oxygen (O) all have varying electron affinities due to differences in their electronic configurations and atomic structures.

Carbon (C):

Carbon has a relatively small atomic radius compared to nitrogen and oxygen.
When an electron is added to a carbon atom to form a C⁻ ion, it experiences a favorable energy change because the electron is added to a relatively small electron cloud. The electron and the nucleus are closer to each other, resulting in a strong electrostatic attraction.
Therefore, carbon has a relatively high electron affinity.
Oxygen (O):

Oxygen has a higher electron affinity compared to carbon because oxygen has a smaller atomic radius and higher effective nuclear charge.
Due to the smaller size and higher effective nuclear charge, the added electron experiences a stronger attraction towards the nucleus, leading to a more significant energy release upon electron addition.
Oxygen's electron affinity is higher than that of carbon, meaning it has a greater tendency to gain electrons.
Nitrogen (N):

Nitrogen has a larger atomic radius compared to both carbon and oxygen.
While nitrogen does have a stronger effective nuclear charge than carbon, it has a larger atomic radius which means that the added electron is further away from the nucleus compared to carbon and oxygen.
As a result, the added electron in nitrogen is not held as strongly by the nucleus, leading to a less favorable energy change upon electron addition.
Therefore, nitrogen's electron affinity is lower (less negative) than those of both carbon and oxygen.
In summary, the differences in electron affinity among nitrogen, carbon, and oxygen can be attributed to variations in atomic radius, effective nuclear charge, and electron-electron repulsions within their electron clouds.