Copper Valence Explained

The valence of an atom refers to its combining capacity with other atoms. It is determined by the number of electrons in the outermost shell of an atom that can be gained, lost, or shared during chemical reactions. For the copper atom, understanding its electron configuration is key to determining its valence.

Electron Configuration of Copper

Copper (Cu) is a transition metal with an atomic number of 29. Its electron configuration is somewhat unique due to the stability gained from a fully filled d-subshell. The ground state electron configuration of a copper atom is typically written as:

• \(\text{[Ar]} 3d^{10} 4s^1\)

This configuration shows that copper has one electron in its outermost 4s shell. While the \(3d\) subshell is full, the \(4s\) electron is the most readily available for chemical bonding.

Valence Electron in Copper

The electron in the 4s orbital is the primary valence electron for copper in many of its compounds. When this single 4s electron is lost, the copper atom forms an ion with a +1 charge. This loss results in a stable configuration with a full \(3d^{10}\) subshell, which contributes to its stability.

Therefore, the most common and often considered primary valence for copper is +1, reflecting the loss of this single 4s electron. This results in the Cu⁺ ion.

Common Oxidation States of Copper

Copper can exhibit two common oxidation states, which are also its valencies:

• Copper(I) or Cuprous: In this state, copper loses its single 4s electron, resulting in a +1 charge. This is a very stable state due to the full \(3d^{10}\) subshell.
• Copper(II) or Cupric: In this state, copper loses both its 4s electron and one 3d electron, resulting in a +2 charge. This state is also very common and stable, often seen in aqueous solutions.

Given the options, the electron valence of a copper atom that represents the loss of its outermost electron is +1.

Step-by-Step Valence Determination

1. Identify Atomic Number: Copper (Cu) has an atomic number of 29.
2. Write Electron Configuration: The electron configuration is \(\text{[Ar]} 3d^{10} 4s^1\).
3. Identify Outermost Electrons: The outermost electron is in the 4s orbital. There is 1 electron in the 4s orbital.
4. Determine Most Readily Lost Electron: The 1 electron in the 4s orbital is the most easily lost electron because it is the furthest from the nucleus.
5. Assign Valence: When this single 4s electron is lost, the copper atom forms a \(Cu^+\) ion, meaning its valence is +1.

This process highlights why +1 is a fundamental electron valence for a copper atom.