Aktinium

Kemiallinen merkki: Ac
Järjestysluku: 89
Kategoria: aktinoidit
Ryhmä: 3
Jakso: 7
Lohko: f
Moolimassa: (227) g/mol
Elektronia kuorilla: 2, 8, 18, 32, 18, 9, 2
CAS-numero: 7440-34-8
Olomuoto: kiinteä
Tiheys: 10 kg/l (lähellä huoneenlämpöä)
Sulamispiste: (circa) 1323 K (1050 °C, 1922 °F)
Kiehumispiste: 3471 K (3198 °C, 5788 °F)
Kiderakenne: cubic face centered
Hapetusluvut: 3
Elektronegatiivisuus: 1,1 (Pauling-asteikko)
Nimen alkuperä: aktinos
Nimen tarkoitus: a Greek word which means a beam
Faktoja:
- 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