At the turn of the nineteenth century, about 30 elements were known. 50 years later by the 1850s, scientists had discovered sixty three chemical elements and the numbers kept increasing. With the discovery and study of more and more elements and their compounds, the various data about them also increased. It became progressively difficult to organize all that was known about the elements and scientists made several attempts to look for some pattern in their properties, on the basis of which they could organize study such a large number of elements with ease.Initially scientists had classified elements into metal and non-metals. However, some elements possessed properties which could neither be classified as metals nor non-metals called metalloids. This classification was found to be insufficient for scientific study. Later on, a number of chemists attempted to make a rational and systematic classification of the physical and chemical properties of elements and tabulate the results in the form of a table.