Question

1. what is the correct ground state electron configuration for an atom of silicon (si), which has an atomic number of 14?

options:
1s² 2s² 2p⁶ 3s² 3d⁴
1s² 2s² 2p⁶ 3s² 3p²
1s² 2s² 2p⁶ 3s² 3p²
1s² 2s² 2p⁶ 3s² 3d²
clear all

Explanation:

Step1: Recall electron configuration rules

Electrons fill orbitals in order of increasing energy: \(1s < 2s < 2p < 3s < 3p < 4s < 3d \dots\). The maximum electrons in \(s\)-orbital is 2, \(p\)-orbital is 6, \(d\)-orbital is 10. Silicon (atomic number 14) has 14 electrons.

Step2: Fill orbitals step by step

• \(1s\) orbital: holds 2 electrons (\(1s^2\)).
• \(2s\) orbital: holds 2 electrons (\(2s^2\)).
• \(2p\) orbital: holds 6 electrons (\(2p^6\)) (total so far: \(2 + 2 + 6 = 10\)).
• \(3s\) orbital: holds 2 electrons (\(3s^2\)) (total: \(10 + 2 = 12\)).
• Remaining electrons: \(14 - 12 = 2\), which go to \(3p\) orbital (\(3p^2\)).

So the electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^2\). The second and third options (they are the same) match this.

Answer:

B. \(1s^2 2s^2 2p^6 3s^2 3p^2\) (and C. \(1s^2 2s^2 2p^6 3s^2 3p^2\) as they are identical; assuming the second and third options are the correct ones with this configuration)