You searched for: “actinium
A radioactive element found in uranium ores, used 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 and thorium and polonium and lead and helium; uraninite in massive form is called pitchblende which is the chief uranium ore).

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

Its longest lived isotope is Ac 227 with a half-life of 21.6 years. Atomic number 89; melting point 1,050°C; boiling point (estimated) 3,200°C; specific gravity (calculated) 10.07; valence 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)