Frankium

Kemiallinen merkki: Fr
Järjestysluku: 87
Kategoria: alkalimetallit
Ryhmä: 1
Jakso: 7
Lohko: s
Moolimassa: [223] g/mol
Elektronia kuorilla: 2, 8, 18, 32, 18, 8, 1
CAS-numero: 7440-73-5
Olomuoto: kiinteä
Tiheys: 1,87 kg/l (lähellä huoneenlämpöä)
Sulamispiste: 300 K (27 °C, 80 °F)
Kiehumispiste: 950 K (677 °C, 1250 °F)
Kiderakenne: cubic body centered
Hapetusluvut: 1
Elektronegatiivisuus: 0,7 (Pauling-asteikko)
Nimen alkuperä: francium
Nimen tarkoitus: France, the discoverer's homeland
Faktoja:
- all isotopes of francium decay into either astatine, radium, or radon
- was formerly known as eka-caesium and actinium K
- as little as 20-30 g of francium-223 exists at any given time throughout the Earth's crust
- is the least stable of the naturally occurring elements: its most stable isotope, francium-, 233 has a half-life of only 22 minutes
- has the lowest electronegativity of all the known elements at 0,7 on the Pauling scale