Actinium
actinium atom
Identifikatoren & physikalische Daten
| CAS No. | 7440-34-8 |
|---|---|
| Summenformel | Ac |
| Durchschnittliche Molmasse | 227,0278 g/mol |
| Monoisotopische Masse | 227,02775 g/mol |
| SMILES | [Ac] |
| InChIKey | QQINRWTZWGJFDB-UHFFFAOYSA-N |
| PubChem CID | 23965 |
| ChEBI | CHEBI:33337 |
| DTXSID | DTXSID10225388 |
Chemische & physikalische Eigenschaften
| Polarare Oberfläche (TPSA) | 0 |
|---|---|
| H-Brücken-Donoren | 0 |
| H-Brücken-Akzeptoren | 0 |
| Frei drehbare Bindungen | 0 |
| Schwere Atome | 1 |
| Formalladung | 0 |
| Komplexität | 0 |
| Stoffklassen | Physical/Radiation -> Radionuclides |
| SpringerMaterials Properties | electron density of states |
| Physical Description | Cubic crystals with a melting point of 1050 degrees C[Merck Index # 137] |
| Schmelzpunkt | 1050 ±50° |
| Siedepunkt | bp ~3300° |
| Dichte | d25 10.07 |
| Aggregatzustand | silvery metal |
| Farbe | silvery metalcubic |
Sicherheit & Vorschriften
| Gefahrenübersicht | Of all Actinium radionuclides, Actinium-227 (14952-40-0) has the longest half life at 21.77 years. Mode of decay is alpha, beta, and gamma emission. Ac-228 has a half life of 6 hours and decays by beta and gamma emission. [Merck Index # 137] Internal toxicity is Very High for Ac-227 (ALI = 0.004 mCi) and Ac-225 (ALI = 0.005 mCi) and High for Ac-228 (ALI = 0.02 mCi)Lung clearance half-time is >100 days for oxides and hydroxides, 10-100 days for halides and nitrates, and <10 days for other compounds. [NRC ALIs] The specific gamma ray constant for Ac-227 = ~2.2 [Gusev, p. 587] See Radiation, ionizing. |
|---|
Anwendungen & Verwendung
Beschreibung
Actinium-227 occurs in uranium ore and is a decay product of uranium-235. It is found in equilibrium with its decay products. It is prepared by bombarding radium atoms with neutrons. Chemically, the metal is produced by reducing actinium fluoride with lithium vapor at 1,100℃ to 1,300℃. AcF3+Li→Ac + 3LiF The element was discovered independently by A. Debierne and F. Giesel in 1899 and 1902, respectively. It is used in nuclear reactors as a source of neutrons.
Occurrence
Actinium-227 occurs in uranium ore and is a decay product of uranium-235. It is found in equilibrium with its decay products. It is prepared by bombarding radium atoms with neutrons. Chemically, the metal is produced by reducing actinium fluoride with lithium vapor at 1,100°C to 1,300°C. AcF3+Li→Ac + 3LiF The element was discovered independently by A. Debierne and F. Giesel in 1899 and 1902, respectively. It is used in nuclear reactors as a source of neutrons.
History
The name Actinium derives from the Greek, aktis or akinis for “beam or ray” because in equilibrium with its decay products, actinium is a powerful source of alpha radiation. The discovery has been credited to the French chemist Andre-Louis Debierne in 1899. It was independently discovered by German chemist Friedrich Oskar Giesel in 1902, who called it emanium. It is thought that Debierne’s original preparation actually consisted of two thorium isotopes, 227Th and 230Th, but there was confusion in those early discoveries in radioactivity and Debierne’s claim prevailed and his name of actinium has been retained to this day. The longest half-life associated with this unstable element is 21.77 year 227Ac.