The properties of non-metals
Non-metals exist as free elements and also combined with other elements as compounds. Unlike the metals, they are not all solids.
| State at ordinary temperature | Non-metals |
|---|---|
| Solid | Carbon, sulphur, phosphorus, iodine |
| Liquid | Bromine |
| Gas | Chlorine, fluorine, hydrogen, nitrogen, oxygen |
Physical properties
- They have no metallic lustre.
- They cannot be beaten into a sheet or drawn out like a wire, and most of them are brittle.
- They are poor conductors of electricity and heat — graphite is the exception. It is one of the allotropic forms of carbon, and although a non-metal it conducts electricity.
- Their density is relatively low — diamond is the exception, another form of carbon, and its density is high.
Chemical properties
- Non-metals form negative ions — anions.
- The oxides they form with oxygen are mostly acidic oxides. These are often gases, and they dissolve in water to form acids.
The opposite of the metals, point by point
Metals give electrons away and form positive ions and basic oxides. Non-metals take electrons in and form negative ions and acidic oxides. Carbon breaks the physical rules twice over — but never the chemical ones.