Protactinium
91Pa · Brevium · Protactinio · Chebi:33386 · protactinium · protactinium atom
Identifikatoren & physikalische Daten
| CAS No. | 7440-13-3 |
|---|---|
| Summenformel | Pa |
| Durchschnittliche Molmasse | 231,0359 g/mol |
| Monoisotopische Masse | 231,03588 g/mol |
| SMILES | [Pa] |
| InChIKey | XLROVYAPLOFLNU-UHFFFAOYSA-N |
| PubChem CID | 23945 |
| ChEBI | CHEBI:33386 |
| EC No. | 616-087-9 |
| DTXSID | DTXSID50225387 |
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 | Shiny, silvery, malleable metalAll isotopes are radioactivePa-231 decays by alpha emission to Actinium-227[Merck Index # 7883] |
| Schmelzpunkt | 1560° |
| Siedepunkt | bp 4227° |
| Dichte | d25 15.37 |
| Aggregatzustand | shiny metal |
| Farbe | shiny metaltetragonal or cubic |
| Spezifische Wärmekapazität | Cp(gas): 0.1 J/(g·K), at 25℃ |
Sicherheit & Vorschriften
| Gefahrenübersicht | Pa-231 decays to Actinium-227 by emitting an alpha particle. Actinium-227 and its decay products account for more than 80% of the inhalation hazard associated with exposure to Pa-231. [Argonne] Most Important Radionuclide: Pa-231 Source: Uranium oresHalf-Life: 33,000 years Specific Activity: 0.048 Ci/g Decay Mode: Alpha GI Absorption: 0.05% Lung Clearance Half-Time: Years for oxides and hydroxidesWeeks for all other compoundsInternal Toxicity: Very High Annual Limit on Intake: 0.000002 mCi Average Radiation Energy (MeV): Alpha 5.0Beta 0.065Gamma 0.048 [Argonne] [See Glossary for references.] See Radiation, ionizing. |
|---|
Anwendungen & Verwendung
History
In 1913 Fajans and Gohring identified the first isotope of this element, a metastable isotope having a mass 234, Pa-234m, a short-lived member of uranium-238 decay series. They named it brevium. In 1918, two independent groups, namely Hahn and Meitner and Soddy, Cranston, and Fleck simultaneously identified a longer-lived isotope Pa-231, a member of the uranium-235 decay series. The isotope Pa-234 in its ground state was discovered by Hahn and Meitner in 1921. The element derived its name from the Greek word protos, which means ‘first.’ Protactinium 231 occurs in the ore pitchblende at about 0.1ppm abundance. Certain ores of pitchblende have a higher abundance of this isotope, about 3ppm. Pa-231 also is found naturally in uranium and radium wastes. No commercial application of protactinium isotopes is known.
Verwenden
233Pa as intermediate in production of fissile 233U in thorium breeder reactors.