Question

How could one describe a metal crystal?
Metal atoms held together by covalent bonds
Positive metal ions surrounded by freely moving valence electrons

Answer 1

A metal crystal can be described as a structured arrangement of metal atoms that are held together by a unique type of bonding known as metallic bonding. In this model, the metal atoms release some of their valence electrons, which become delocalized and form a "sea of electrons." Here’s how the description can be expanded:

1. **Metallic Bonding**: In a metal crystal, metal atoms lose some of their electrons, and these electrons are not associated with any specific atom. Instead, they form a collective pool that can move freely throughout the structure. This delocalization allows metals to conduct electricity and heat effectively.

2. **Structure**: Metal crystals have a highly organized, repeating lattice structure where the metallic cations (the positively charged metal ions) are arranged in a regular pattern. This ordered arrangement contributes to the characteristic properties of metals, such as malleability and ductility.

3. **Properties**: The presence of freely moving valence electrons gives metals their characteristic properties:
- **Conductivity**: The delocalized electrons can transfer energy efficiently, making metals good conductors of electricity and heat.
- **Luster**: The ability of the free electrons to reflect light results in the shiny appearance of metals.
- **Malleability and Ductility**: When stress is applied, metal atoms can slide past one another without breaking the metallic bond, allowing metals to be shaped or drawn into wires.

In summary, a metal crystal consists of positively charged metal ions surrounded by a 'sea of electrons,' contributing to the unique properties and behavior of metallic substances.