Which is the correct electron configuration for Sb 2+ in its ground state? Key Concept: Aufbau principle. Electron configuration for ions is determined the same way as with atoms. Count up the total number of electrons in the atom and start filling orbitals from low energy to higher energy.
A 1s22s22p63s23p64s23d64p64d105p4
B 1s22s22p63s23p64s23d104p45s24d105p2
C 1s22s22p63s23p64s23d104p65s24d105p1
D 1s22s22p53s23p64s23d104p64d105p1
The Correct Answer and Explanation is:
The correct answer is: C
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p¹
Explanation
To determine the ground-state electron configuration of Sb²⁺ (antimony ion with a +2 charge), we need to understand the Aufbau principle, which states that electrons fill orbitals from lowest to highest energy.
Step 1: Determine atomic number and electron configuration of neutral Sb
Antimony (Sb) has an atomic number of 51, meaning a neutral Sb atom has 51 electrons. The ground-state electron configuration of neutral Sb is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p³
(Total: 2 + 2 + 6 + 2 + 6 + 2 + 10 + 6 + 2 + 10 + 3 = 51 electrons)
Step 2: Remove electrons to get Sb²⁺
When forming a 2+ cation, two electrons are removed, and they are removed from the outermost orbitals (highest principal quantum number, n), following the Aufbau principle in reverse.
The outermost electrons are in the 5p and 5s orbitals (n = 5). Since 5p has 3 electrons and 5s has 2 electrons, we remove two electrons from the 5p orbital (as p-electrons are higher in energy than s-electrons in the same shell).
So, removing 2 electrons from 5p³ results in 5p¹, and the configuration becomes:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p¹
This corresponds to Option C, which is the correct configuration for Sb²⁺ in its ground state.
Why Other Options Are Incorrect:
- Option A: Incorrect orbital filling and incorrect number of electrons.
- Option B: Misplaced electron configuration; 3d⁶ instead of 3d¹⁰.
- Option D: Contains errors in the 2p orbital and other inconsistencies.
Thus, based on the Aufbau principle and proper electron removal for cations, Option C is correct.
