Protactinium (Pa)
Protactinium (Pa) is element 91 of the periodic table, an actinide in period 7, in the f-block. Its standard atomic weight is 231.03588, so one mole of protactinium atoms has a mass of 231.03588 g. At room temperature it is a solid.
| Atomic number | 91 |
|---|---|
| Symbol | Pa |
| Standard atomic weight | 231.03588 |
| Molar mass | 231.03588 g/mol |
| Category | Actinide |
| Group | f-block (actinide series) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 7s2 5f2 6d1 |
| Oxidation states | +5, +4 |
| Electronegativity (Pauling) | 1.5 |
| Atomic radius (van der Waals) | 243 pm |
| First ionisation energy | 5.89 eV (568.3 kJ/mol) |
| Electron affinity | — |
| State at room temperature | Solid |
| Melting point | 1845 K (1571.85 °C) |
| Boiling point | — |
| Density | 15.37 g/cm³ |
| Discovered | 1913 |
Actinides
Ac · ActiniumTh · ThoriumU · UraniumNp · NeptuniumPu · PlutoniumAm · AmericiumCm · CuriumBk · BerkeliumCf · CaliforniumEs · EinsteiniumFm · FermiumMd · MendeleviumNo · Nobelium
Calculate with Protactinium
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.