Which of the following describes ionic properties of compounds?

• A. Low melting points, soluble in water, no odor, usually solid, hard, conducts electricity.
• B. High melting points, soluble in water, no odor, usually solid, hard, conducts electricity.
• C. Gases at room temperature with no solubility in water.
• D. Always liquids at room temperature.

Answer: (B)

Ionic compounds form a crystal lattice held together by strong electrostatic forces between oppositely charged ions, so a lot of energy is needed to break them apart. That makes their melting points very high, and they tend to be solid and hard at room temperature. Water’s polarity helps dissolve many of them by surrounding and stabilizing the individual ions, which is why they’re often soluble in water. When melted or dissolved, the ions are free to move, so the substance can conduct electricity. So the description that fits best is: high melting points, soluble in water, usually solid, hard, and conducts electricity (in the molten or dissolved state). The other options clash with these common properties—ionic compounds aren’t typically low melting point, gaseous at room temperature, or always liquids.