Which of the following best explains why metals generally have high melting and boiling points?

• A. Metals have covalent bonds between their atoms.
• B. Metals consist of molecules held together by hydrogen bonding.
• C. Metals have weak van der Waals forces between their atoms.
• D. Metals have strong metallic bonds due to the attraction between delocalized electrons and positive metal ions.

Answer: (D)

Verified step by step guidance

1. Understand the nature of bonding in metals: Metals consist of a lattice of positive metal ions surrounded by a 'sea' of delocalized electrons that are free to move throughout the structure.
2. Recognize that this type of bonding is called metallic bonding, which is characterized by the electrostatic attraction between the positively charged metal ions and the negatively charged delocalized electrons.
3. Recall that strong metallic bonds require a significant amount of energy to break because the attraction between the ions and electrons holds the metal atoms tightly together in a solid structure.
4. Compare metallic bonding to other types of intermolecular forces such as covalent bonds, hydrogen bonding, and van der Waals forces, noting that metallic bonds are generally stronger and more extensive in metals.
5. Conclude that the strong metallic bonding explains why metals generally have high melting and boiling points, as a large amount of energy is needed to overcome these strong attractions and change the metal from solid to liquid or gas.