Protactinium (Pa) — Element 91: Properties & Data | Aladdin Scientific
Protactinium(Pa) — Element 91
Protactinium (Pa) is a actinide with atomic number 91 and atomic mass 231.036. It has melting point 1845 K (1572 °C), density 15.37 g/cm³. It sits in period 7 of the periodic table and was discovered in 1913.
Key facts
| Atomic mass | 231.0359 u |
|---|---|
| Electron configuration | [Rn]7s2 5f2 6d1 |
| Oxidation states | +5, +4 |
| Electronegativity (Pauling) | 1.5 |
| Atomic radius (van der Waals) | 243 pm |
| Ionization energy | 5.89 eV |
| Melting point | 1845 K |
| Density | 15.37 g/cm³ |
| Standard state | Solid |
| Year discovered | 1913 |
Frequently asked questions
What is the electron configuration of protactinium?
The ground-state electron configuration of protactinium is [Rn]7s2 5f2 6d1.
What group and period is protactinium in?
Protactinium (Pa) is in period 7 (actinide series) of the periodic table, classified as a actinide.
What is the melting point of protactinium?
Protactinium melts at 1845 K (1572 °C).
What is the standard state of protactinium?
Protactinium is a solid at standard temperature and pressure.
Related elements
About this data: property values compiled from IUPAC Standard Atomic Weights (2021), the NIST Atomic Spectra Database, and PubChem. Curated by the Aladdin Scientific technical team. Last reviewed: .