1. Poor conductors of heat and electricity: Non-metals generally resist the flow of heat and electricity. This is why materials like rubber and plastic are used as insulators.

2. Dull appearance: Most non-metals lack the shiny luster that is characteristic of metals. They tend to be brittle and easily broken.

3. Low density: Non-metals are generally less dense than metals, meaning they have a lower mass per unit volume.

4. Gases at room temperature: Many non-metals exist as gases at room temperature, such as oxygen, nitrogen, and chlorine. A few are liquids (like bromine) and some are solids (like sulfur and carbon).