organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic number. Scientists use the periodic table to quickly refer to information ...

Elements are placed in order of increasing atomic number, which is the number of protons in an atom's nucleus. The table is divided into rows called periods and columns called groups or families.

Cal: And what about these vertical columns? I mean, what does all of that mean? Mrs Roberts: Well, elements that have similar properties to each other are put into vertical columns called groups.