Question

The element having \([Ar]3d^{10}4s^1\) electronic configuration is

• A. Cu
• B. Zn
• C. Cr
• D. Mn

Hint:

Copper (Cu) has an electron configuration of \( [Ar] 3d^{10} 4s^1 \), which is an exception to the general electron configuration rule due to stability gained by a filled 3d subshell.

Answer 1

The Correct Option is A

To solve the problem, we need to identify the element with the electronic configuration [Ar]3d\(^{10}\)4s\(^1\).

1. Understanding the Configuration:
The configuration [Ar] represents the electron configuration of argon, which is 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\), accounting for 18 electrons. The additional 3d\(^{10}\)4s\(^1\) indicates:
- 3d\(^{10}\): 10 electrons in the 3d subshell.
- 4s\(^1\): 1 electron in the 4s subshell.
Total electrons = 18 (from [Ar]) + 10 (3d) + 1 (4s) = 29 electrons.

2. Determining the Element:
The number of electrons in a neutral atom equals its atomic number. An element with 29 electrons has an atomic number of 29, which corresponds to copper (Cu) on the periodic table.

3. Verifying the Configuration:
Copper (Cu, atomic number 29) has the expected ground state configuration. The noble gas core [Ar] is followed by the filling of the 4s and 3d orbitals. Typically, for transition metals, the 4s orbital fills before 3d. However, copper is an exception:
- Expected: [Ar]4s\(^2\)3d\(^9\)
- Actual: [Ar]4s\(^1\)3d\(^{10}\)
This exception occurs because a fully filled 3d subshell (3d\(^{10}\)) is more stable than a partially filled one, so an electron from 4s moves to 3d, resulting in [Ar]3d\(^{10}\)4s\(^1\), which matches the given configuration.

Final Answer:
The element with the electronic configuration [Ar]3d\(^{10}\)4s\(^1\) is copper (Cu).