Give the main characteristics of representative elements.

1. They include both metals and non-metals. There is a regular gradation from metallic to non-metallic character as one moves from left to right across the period.
2. They form electrovalent as well as covalent compounds with non-metals.
3. Metallic nature increases on moving down any of these seven groups.
4. Metals, which are good conductors of heat and electricity, are present in groups 1 and 2. Non-metals, which are present in groups 16 and 17, are poor conductors of heat and electricity.
5. Some heavier elements, like tin and lead, exhibit variable valencies.