Question

Which of the following is the correct electronic configuration for \( \text{Oxygen (O)} \)?

• A. \( 1s^2 2s^2 2p^4 \)
• B. \( 1s^2 2s^2 2p^6 \)
• C. \( 1s^2 2s^2 2p^3 \)
• D. \( 1s^2 2s^2 3p^2 \)

Hint:

Remember the order of filling orbitals: \( 1s \to 2s \to 2p \to 3s \to 3p \).

Answer 1

The Correct Option is A

Step 1: Determine Oxygen’s atomic number
Oxygen (O) has an atomic number of 8, indicating 8 electrons in a neutral atom.

Step 2: Orbital filling order
Electrons occupy orbitals based on increasing energy:
\[ 1s \to 2s \to 2p \to 3s \to 3p \to \ldots \] Orbital capacities:
- \( 1s \): 2 electrons
- \( 2s \): 2 electrons
- \( 2p \): 6 electrons

Step 3: Electron assignment
For 8 electrons:
- \( 1s^2 \): 2 electrons (filled)
- \( 2s^2 \): 2 electrons (filled, total 4)
- \( 2p^4 \): 4 electrons (total 8)
Electron configuration: \[ 1s^2 2s^2 2p^4 \]
Step 4: Evaluate options
- (1) \( 1s^2 2s^2 2p^4 \): Matches calculation; correct.
- (2) \( 1s^2 2s^2 2p^6 \): Total 10 electrons (Neon); incorrect.
- (3) \( 1s^2 2s^2 2p^3 \): Total 7 electrons (Nitrogen); incorrect.
- (4) \( 1s^2 2s^2 3p^2 \): Incorrect; Oxygen's electrons are in 2p, not 3p.

Step 5: Conclusion
Option (1) represents the correct configuration.