Question

Which of the following elements contains maximum number of unpaired electrons?

• A. Fluorine
• B. Sodium
• C. Nitrogen
• D. Oxygen

Hint:

Always apply Hund's Rule of Maximum Multiplicity. It states that for a given electron subshell (like $p$, $d$, or $f$), every orbital is singly occupied with one electron before any one orbital is doubly occupied, maximizing unpaired spins.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The number of unpaired electrons is determined by the electron configuration of the valence shell using Hund's Rule.

Step 2: Formula Application:
Atomic numbers: N (7), O (8), F (9), Na (11).

Step 3: Explanation:
Nitrogen: $1s^2 2s^2 2p^3$. The three electrons in the $2p$ subshell occupy three separate orbitals. (3 unpaired) Oxygen: $1s^2 2s^2 2p^4$. One $2p$ orbital is paired, two have single electrons. (2 unpaired) Fluorine: $1s^2 2s^2 2p^5$. Two $2p$ orbitals are paired, one has a single electron. (1 unpaired) Sodium: $[Ne] 3s^1$. (1 unpaired)

Step 4: Final Answer:
Nitrogen contains the maximum number of unpaired electrons.