7. Periodic Classification of Element
One hundred and fifteen elements are known till date and many more may be known in future. All elements differ in their properties due to the presence of different kinds of atoms in them. Elements combine to form millions of compounds.
Important Terms and Concepts :
1. Need of Classification : It is difficult to study each and every element individually and to know its properties and uses. Therefore, they have been classified into groups on the basis of their similarities in properties.
2. Classification : Classification means grouping of elements on the basis of similarities in properties, e.g., All of you belong to class X because you resemble in you properties, e.g., All of you have passed class IX, all of you are in age group of 13-15 years.
3. Basis of Classification : Classification is done on the basis of similarities in properties so that the systematic study could be made about them.