Promethium is element number 61, with the symbol Pm. Its name comes from Prometheus, the god of fire in Greek myth.
Atomic number 61(145)
PmPromethiumプロメチウム (purometiumu)
Symbol
Pm
Atomic weight
(145)
Place in the table
Period 6 · Lanthanoids
The number in parentheses is not an atomic weight. It is the mass number of one radioactive isotope of the element.
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
The god of fire
Prometheus is the god of fire in Greek myth. The name promethium is said to link this god of fire with releasing the energy of the atomic nucleus. It was discovered in 1947.
Where it sits on the table
The fifteen elements from lanthanum to lutetium are called the lanthanoids. On the Room of the Elements table they are in the upper of the two rows set apart at the bottom.
Think about it
Q1Why do you think the god of fire’s name was given to a new element?
Q2Collect the elements named after myths in the Room of the Elements.
Q3Why do you think it wasn’t found until 1947?
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — Elements named after gods include promethium (god of fire), thorium (god of thunder) and uranium (god of the sky).