TeXes Science Practice Test

How do free valence electrons in metallic elements benefit conductivity?

1. By creating heat

2. By allowing electrons to move freely

3. By forming ionic bonds

4. By restricting movement

The correct answer is: By allowing electrons to move freely

The correct answer highlights the fundamental characteristic of metallic bonding, which involves free-moving valence electrons. In metallic elements, the outermost electrons are not tightly bound to individual atoms but instead form a "sea of electrons" that can move freely throughout the material. This mobility enables the conduction of electricity, as when an electric field is applied, these free electrons can flow, carrying electrical current through the metal. Heat generation (though it can occur due to resistance in conductive materials) is a secondary effect and not directly the result of electron movement. Ionic bonds, on the other hand, involve the transfer of electrons between atoms and typically do not contribute to the metallic conductivity; they are characteristic of non-metallic compounds. Restricting movement would imply that electrons are trapped or localized, which would hinder rather than facilitate conductivity. Thus, the ability of free valence electrons to move freely is what primarily benefits electrical conductivity in metallic elements.