118 elements and seven periods, though just one period of high school chemistry is enough to get confused by it. This week, we’re exploring the history behind the periodic table.

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 periodic table is one of the triumphs of science. Even before certain elements had been discovered, this chart could successfully predict their masses, densities, how they would link up with other ...