The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

The zigzag, staircase, line in the diagram of the periodic table above separates the metals, on the left, from non-metals, on the right. Hydrogen is a non-metal, but it is often put in the middle.

This year marks the 150th anniversary of the publication of Mendeleev’s Periodic Table of Chemical Elements in 1869. In celebration, the United Nations Educational, Scientific, and Cultural ...