Chemistry 2010 JAMB Past Questions - Question 7: How many unpaired electron(s) are there in the nitrogen sub-levels?

Correct Answer

A

Explanation

There are **three unpaired electrons** in the nitrogen sub-levels. Here's the breakdown:

1. **Electron configuration:** Nitrogen's electron configuration is written as 1s² 2s² 2p³. This denotes the number of electrons in each subshell:
    - 1s subshell: 2 electrons (paired)
    - 2s subshell: 2 electrons (paired)
    - 2p subshell: 3 electrons (3 total, but not all paired)

2. **Hund's rule:** This rule states that electrons will fill orbitals of the same sublevel with single electrons before pairing up. In nitrogen's case, the 2p sublevel has three orbitals (2px, 2py, 2pz). Each of these orbitals gets one electron before any pairing occurs.

Therefore, nitrogen has:

- 2 paired electrons in the 1s sublevel.
- 2 paired electrons in the 2s sublevel.
- 1 unpaired electron in each of the three 2p orbitals.

This adds up to a total of **3 unpaired electrons** in nitrogen.