2. Which of these is generally a property of substances held together by metallic bonding?

Substances held together by metallic bonding generally exhibit the following properties:<br /><br />1. **High Electrical Conductivity**: Metallic bonds allow electrons to move freely throughout the structure, making metals good conductors of electricity.<br /><br />2. **Malleability and Ductility**: Metals can be hammered into thin sheets (malleable) or drawn into wires (ductile) without breaking due to the ability of metal atoms to slide past each other while maintaining the metallic bond.<br /><br />3. **Luster**: Metals typically have a shiny appearance because they reflect light well, which is due to the free electrons on their surface.<br /><br />4. **High Thermal Conductivity**: The free-moving electrons in metals also allow them to conduct heat efficiently.<br /><br />5. **Variable Melting and Boiling Points**: While many metals have high melting and boiling points, there is variability depending on the strength of the metallic bonds in different metals.<br /><br />These properties are characteristic of the "sea of electrons" model in metallic bonding, where electrons are delocalized and shared among a lattice of metal cations.