The periodic table is a tabular display of the chemical elements, which are arranged by their atomic number, electron configuration, and recurring chemical properties. It is generally accepted that the modern periodic table was first published by Dmitri Mendeleyev in 1869, although several other scientists had developed similar tables prior to this.

Mendeleyev's table was based on the idea that the chemical properties of the elements are a periodic function of their atomic masses. He arranged the elements in order of increasing atomic mass, and he grouped together elements with similar chemical properties. This led to the development of the modern periodic table, which is organized into 18 vertical columns, called groups, and 7 horizontal rows, called periods.

The groups are numbered 1-18 from left to right, and the periods are numbered 1-7 from top to bottom. The elements in each group have similar chemical properties, and the elements in each period have the same number of electron shells.

The periodic table is a valuable tool for organizing and understanding the chemical elements. It can be used to predict the chemical properties of an element, and it can also be used to explain the chemical reactions that occur between elements.