It is a well-known fact that elements are the building blocks of various kinds of materials.
Although there are only about 114 elements known, yet they constitute the entire matter on this earth. The elements are classified into three categories, namely: metals, non-metals and metalloids.
Metals are generally lustrous, solids, malleable, ductile and good conductors of heat and electricity. They constitute about two-third of the known elements. Some of the metals which flnd common use in our daily life are : iron, copper, aluminium, lead, gold, silver, mercury, etc.