You searched for: “actinium
actinium (s) (noun) (no pl)
A radioactive metallic chemical element found in uranium ores: Actinium is in equilibrium with its decay products as a source of alpha rays, such as pitchblende, a mineral consisting of uranium oxide and trace amounts of radium, thorium, polonium, lead, and helium. Uraninite in a massive form is called pitchblende which is the chief uranium ore.

Actinium possesses no stable isotopes and exists in nature only as a disintegration product of uranium and thorium.

The longest lived isotope of actinium is Ac 227 with a half-life of 21.6 years. Its atomic number is 89, the melting point is 1,050°C, the estimated boiling point is 3,200°C, and its specific calculated gravity is 10.07, and a valence of 3.

This entry is located in the following units: actino-, actin-, actini-, -actinal, actis- + (page 1) -um (page 1)
Information is located at Chemical Element: actinium.
This entry is located in the following unit: Chemical Elements List (page 1)
A unit related to: “actinium
(Modern Latin: chemical element; from Greek, aktis, aktinos ray; radioactive metal)
(Modern Latin: some say it comes from Greek proto, "first"; plus actinium, "ray"; so, “first actinium”; radioactive metal)