Promethium

Promethium (symbol Pm) is a chemical element, atomic number 61 on the periodic table.

Characteristics and history
Promethium, in its most stable form, has an atomic mass of 145. Promethium was discovered by Humans on Earth's North American continent for the first time by scientists working in the United States in the year 1945. This element is part of the lanthannide series of heavy elements, and was named for the god from Earth's mythology.