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, meaning it has 8 electrons in a neutral atom.

Step 2: Order of orbital filling
Electrons fill orbitals in order of increasing energy:
\[ 1s \to 2s \to 2p \to 3s \to 3p \to \ldots \] Capacities:
- \( 1s \): 2 electrons
- \( 2s \): 2 electrons
- \( 2p \): 6 electrons

Step 3: Assign electrons
For 8 electrons:
- \( 1s^2 \): 2 electrons (filled)
- \( 2s^2 \): 2 electrons (filled, total 4)
- \( 2p^4 \): 4 electrons (total 8)
So, the configuration is: \[ 1s^2 2s^2 2p^4 \]
Step 4: Check options
- (1) \( 1s^2 2s^2 2p^4 \): Correct, matches our calculation.
- (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, as Oxygen’s electrons are in 2p, not 3p.

Step 5: Conclusion
The correct configuration is option (1).