What is the electron configuration of the Cu?¹ ion? -[Ar]4s²3d¹? -[Ar]3d¹? -[Ar]4s²3d? -[Ar]4d? -[Ar]4s²3d?
The Correct Answer and Explanation is:
Correct Answer: [Ar] 3d¹⁰
To understand this, first consider the electron configuration of a neutral copper (Cu) atom, which has an atomic number of 29. This means it has 29 electrons. The expected configuration by Aufbau principle would be:
[Ar] 4s² 3d⁹
However, copper is an exception due to the extra stability provided by a fully-filled d-subshell. So, one electron from the 4s orbital is promoted to the 3d orbital, giving copper the actual ground-state configuration:
[Ar] 4s¹ 3d¹⁰
When copper loses one electron to form the Cu⁺¹ ion, it loses the electron from the 4s orbital first because the 4s orbital is higher in energy than the 3d orbital after filling. Thus, removing one electron from 4s¹ results in:
[Ar] 3d¹⁰
This configuration is particularly stable because a completely filled d-subshell (with 10 electrons) is energetically favorable. It helps explain why Cu⁺ is a commonly found oxidation state for copper in nature.
The incorrect options in the question include configurations such as [Ar] 4s² 3d¹⁰ or [Ar] 4s² 3d⁷, which either violate the actual known configuration of copper or imply incorrect electron loss.
In summary, when copper loses one electron to become Cu⁺¹, it does so from the 4s orbital, leaving behind a stable 3d¹⁰ configuration. Therefore, the most accurate electron configuration of the Cu⁺¹ ion is [Ar] 3d¹⁰.
