Symbol

Po

Atomic Number

84

Atomic Mass

208.9824

Family

Group 16 (Via) Chalcogen Pronunciation

puh-LO-nee-um

Overview

Polonium was discovered in 1898 by Polish-French physicist Marie Curie (1867-1934) and her husband, Pierre (1859-1906). They were looking for the source of radioactivity in a naturally occurring ore called pitchblende. Radioactivity is the process by which materials give off energy and change into new materials.

Polonium is the heaviest element in the chalcogen family. It is in Group 16 (VIA) on the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. The other chalcogen elements are oxygen, sulfur, selenium, and tellurium.

Polonium is a relatively rare element. The pitchblende studied by the Curies contained only about 100 micrograms (millionths of a gram) of polonium per metric ton of ore. The element can now be prepared artificially in a particle accelerator, or "atom smasher." It causes small particles such...