TeXes Science Practice Test

What is the state of the valence electrons in copper?

1. Completely bound

2. Essentially free

3. Fixed in position

4. Limited mobility

The correct answer is: Essentially free

In copper, the valence electrons are considered to be essentially free due to the nature of metallic bonding. In metals like copper, the outermost electrons are not bound to any specific atom; instead, they form what is known as an "electron sea." This allows the valence electrons to move freely throughout the metal lattice, contributing to various properties such as electrical conductivity and malleability. The ability of these electrons to move easily under the influence of an electric field is what characterizes them as essentially free, enabling the flow of electric current when voltage is applied. The other options suggest different states of electron behavior that do not accurately describe the metallic nature of copper's valence electrons. For example, saying they are completely bound would imply that they are tightly held by atomic nuclei, which is not the case in metals where electron mobility plays a key role in their properties. Similarly, fixed in position or limited mobility does not apply to the highly mobile and loosely held nature of electrons in metals.