Non-metals are basically defined as elements that are not metals.

Their physical properties generally include:

1. They are poor conductors.
2. They are brittle, not ductile in their solid state.
3. They show no metallic luster.
4. They may be transparent or translucent.
5. They have low density.
6. They are gases, liquids, or solids.
7. They form molecules which consists of atoms covalently bonded; the nobel gases are monoatomic.

Their chemical properties are generally:

1. They usually have four to eight valence electrons.
2. They have high electron affinities. (except noble gases)
3. They are good oxidizing agents. (except noble gases)
4. They have hydroxides which are acidic. (except noble gases)
5. They are electronegative.