What is the periodic table?

The periodic table is a tabular display of the chemical elements, organized on the basis of their properties. Elements are presented in increasing atomic number. While rectangular in general outline, gaps are included in the rows or periods to keep elements with similar properties together, such as the halogens and the noble gases, in columns or groups, forming distinct rectangular areas or blocks. Because the periodic table accurately predicts the properties of various elements and the relations between properties, its use is widespread within chemistry, providing a useful framework for analysing chemical behavior, as well as in other sciences.