Question

Which element has '2, 8, 1' Electronic configuration?

• A. K
• B. Mg
• C. Al
• D. Na

Hint:

To determine the element corresponding to a given electronic configuration, count the total number of electrons in each shell. For '2, 8, 1', the total number of electrons is $ 2 + 8 + 1 = 11 $, which corresponds to sodium (Na). Always remember that the electronic configuration reflects the distribution of electrons across different energy levels.

Answer 1

The Correct Option is D

Step 1: Analyze the Electronic Configuration.
The electronic configuration '2, 8, 1' indicates that the element has:
2 electrons in the first shell (K-shell),
8 electrons in the second shell (L-shell),
1 electron in the third shell (M-shell).
This configuration corresponds to the element sodium (Na), which has an atomic number of 11. The full electronic configuration of sodium is: $$ 1s^2 \, 2s^2 \, 2p^6 \, 3s^1, $$ which simplifies to '2, 8, 1'. Step 2: Analyze Each Option.
Option (1): K — Incorrect, as potassium (K) has an electronic configuration of '2, 8, 8, 1'.
Option (2): Mg — Incorrect, as magnesium (Mg) has an electronic configuration of '2, 8, 2'.
Option (3): Al — Incorrect, as aluminum (Al) has an electronic configuration of '2, 8, 3'.
Option (4): Na — Correct, as sodium (Na) has the electronic configuration '2, 8, 1'. Step 3: Final Answer. $$ (4) \mathbf{\text{Na}} $$