We know by now that the elements are the basic units of all types of matter. In 1800, only 31 elements were known. By 1865, the number of identified elements had more than doubled to 63.
At present 114 elements are known. Of them, the recently discovered elements are man-made. Efforts to synthesise new elements are continuing.
With such a large number of elements it is very difficult to study individually the chemistry of all these elements and their innumerable compounds individually.
To ease out this problem, scientists searched for a systematic way to organise their knowledge by classifying the elements. Not only that it would rationalize known chemical facts about elements, but even predict new ones for undertaking further study.