Question

the atomic number of silicon (si) is 14. whats the electron configuration for silicon?
a) he 1s² 2p⁶
b) ar 3p⁵
c) ne 3s² 3p²
d) he 2s² 3p²

Explanation:

To determine the electron configuration of silicon (atomic number 14), we follow the Aufbau principle. The electron configuration of neon (Ne) is \(1s^2 2s^2 2p^6\). Silicon has 14 electrons, so after the \(1s^2 2s^2 2p^6\) (which is [Ne]), we fill the 3s orbital (2 electrons) and then the 3p orbital with 2 electrons (since \(14 - 10 = 4\), and \(3s^2\) uses 2, leaving 2 for \(3p\)). So the electron configuration is \([Ne] 3s^2 3p^2\).

• Option A: \([He] 1s^2 2p^6\) has \(2 + 2 + 6 = 10\) electrons, not 14.
• Option B: \([Ar] 3p^5\) has \(18 + 5 = 23\) electrons, not 14.
• Option D: \([He] 2s^2 3p^2\) has \(2 + 2 + 2 = 6\) electrons, not 14.

Only Option C matches the electron count and correct orbital filling for silicon.

Answer:

C) \([Ne] 3s^2 3p^2\)