What is the ground-state electron configuration of the ion Cu+?
A) [Ar]4s2 3d8
B) [Ar]4s1 3d10
C) [Ar]3d10
D) [Ar]4s2 3d10 4p1
The correct answer and explanation is :
The correct answer is: C) [Ar] 3d¹⁰
Explanation:
To determine the ground-state electron configuration of Cu⁺ (Copper(I) ion), we need to start by understanding the configuration of neutral copper (Cu) and how it changes upon losing an electron.
Step 1: Electron Configuration of Neutral Cu
The atomic number of Copper (Cu) is 29, which means it has 29 electrons in its neutral state.
The expected configuration from the periodic table should follow the order of filling:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁹
However, copper is an exception to the expected order due to enhanced stability of a full d-subshell.
So, the actual ground-state configuration of Cu is:
[Ar] 4s¹ 3d¹⁰
This configuration is energetically more favorable because a completely filled 3d subshell (3d¹⁰) is more stable than a 3d⁹ configuration.
Step 2: Forming the Cu⁺ Ion
When copper loses one electron to become Cu⁺, that electron is removed from the 4s orbital first, not the 3d orbital. This is because:
- Even though the 4s orbital is filled before the 3d orbital, it is higher in energy once the 3d orbitals begin to fill.
- Thus, the 4s electron is removed first when ionizing.
So, we remove one electron from the 4s¹ in the neutral atom [Ar] 4s¹ 3d¹⁰, leaving:
[Ar] 3d¹⁰
Step 3: Eliminate Other Options
- A) [Ar] 4s² 3d⁸ – Incorrect, this is not a stable or expected configuration for Cu⁺.
- B) [Ar] 4s¹ 3d¹⁰ – This is the configuration of neutral Cu, not Cu⁺.
- C) [Ar] 3d¹⁰ – ✅ Correct configuration for Cu⁺.
- D) [Ar] 4s² 3d¹⁰ 4p¹ – Incorrect; this would be for an element with atomic number 31 (Gallium).
Summary:
Cu⁺ has lost its 4s¹ electron, resulting in a configuration of [Ar] 3d¹⁰. This is a full and stable d-subshell, making it the correct ground-state configuration.
Would you like a similar explanation for Cu²⁺?