A piece of sodium metal can be described as:

• A. a compound formed by sodium and chlorine atoms
• B. a mixture of sodium ions and electrons
• C. a lattice of sodium molecules
• D. a collection of sodium atoms held together by metallic bonds

Answer: (D)

Verified step by step guidance

1. Understand the nature of metallic bonding: Metallic bonds occur between metal atoms where valence electrons are delocalized and shared across a lattice of metal cations.
2. Recognize that sodium metal consists of sodium atoms arranged in a regular lattice structure, not molecules or ions separated from each other.
3. Eliminate options that describe sodium metal as a compound with chlorine atoms or as a mixture of ions and electrons, since pure sodium metal contains only sodium atoms.
4. Recall that in metallic bonding, the atoms are held together by a 'sea of electrons' that are free to move, which explains properties like electrical conductivity and malleability.
5. Conclude that sodium metal is best described as a collection of sodium atoms held together by metallic bonds, rather than molecules, ions, or compounds.