Which type of substance do covalent bonds typically form at room temperature?

• A. Crystalline solids with high melting points
• B. Ionic compounds that conduct electricity in solution
• C. Metallic solids with delocalized electrons
• D. Molecules with low melting and boiling points

Answer: (D)

Verified step by step guidance

1. Understand that covalent bonds involve the sharing of electron pairs between atoms, typically nonmetals, forming discrete molecules rather than extended lattices.
2. Recognize that substances formed by covalent bonds usually exist as individual molecules rather than continuous networks, which affects their physical properties.
3. Recall that molecular substances held together by covalent bonds tend to have relatively weak intermolecular forces (like Van der Waals forces or hydrogen bonds), leading to lower melting and boiling points.
4. Contrast this with ionic compounds, which form crystalline solids with high melting points due to strong electrostatic attractions, and metallic solids, which have delocalized electrons and different properties.
5. Conclude that at room temperature, covalent bonds typically form molecular substances characterized by low melting and boiling points, rather than crystalline solids or metallic solids.