Symbol: Ac
Atomic number: 89
Category: actinides
Group: 3
Period: 7
Block: f
Atomic weight: (227) g/mol
Electrons per shell: 2, 8, 18, 32, 18, 9, 2
CAS number: 7440-34-8
Phase: solid
Density: 10 kg/dm3 (near room temperature)
Melting point: (circa) 1323 K (1050 °C, 1922 °F)
Boiling point: 3471 K (3198 °C, 5788 °F)
Crystal structure: cubic face centered
Oxidation states: 3
Electronegativity: 1.1 (Pauling scale)
Name's origin: aktinos
Name's meaning: a Greek word which means a beam
Facts:
- was the first non-primordial radioactive element to be isolated, although polonium, radium and radon were observed before, but not isolated until 1902
- gave the name to the actinoid series
- is a silvery, radioactive, metallic element
- due to its intense radioactivity, actinium glows in the dark with a pale blue light
- is found in trace amounts in uranium ore, but more commonly is made in milligram amounts by the neutron irradiation of radium-226 in a nuclear reactor
- actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300°C
- is about 150 times as radioactive as radium, making it valuable as a neutron source for energy
- has no significant industrial applications
- is even more dangerous than plutonium, and ingesting even small amounts of actinium-227 would be fatal
- naturally occurring actinium is composed of 1 radioactive isotope with a half-life of 21.772 years