Protactinium
Protactinium (镤, symbol Pa) is chemical element number 91, an Actinide in period 7 of the periodic table, with a standard atomic weight of about 231.04. Dense, silvery-gray, radioactive actinide. One of the rarest natural elements.
Properties
| Atomic number | 91 |
|---|---|
| Symbol | Pa |
| Atomic mass | 231.04 u |
| Category | Actinide |
| Period | 7 |
| Group | — |
| Electron configuration | [Rn] 5f² 6d¹ 7s² |
| Electronegativity | 1.5 |
| Covalent radius | 200 pm |
| Density | 15.37 g/cm³ |
| Melting point | 1841 K |
| Boiling point | 4300 K |
| Discovery | Hahn & Meitner, 1913 |
Overview
Dense, silvery-gray, radioactive actinide. One of the rarest natural elements. Protactinium (Pa) holds position 91 in the periodic table, an Actinide in period 7. As an actinide it is typically radioactive and closely tied to nuclear technology.
With 2 electrons in its outermost shell, Protactinium bonds accordingly; full configuration [Rn] 5f² 6d¹ 7s², electronegativity 1.5. At room temperature it is normally a solid; it melts near 1841 K (1567.9 °C), boils near 4300 K (4026.9 °C), has a density around 15.37 g/cm³.
Common applications range across Research. On the safety side, it carries a high hazard rating. It was first described by Hahn & Meitner in 1913.
Electron shells
Electrons per shell: 2 · 8 · 18 · 32 · 20 · 9 · 2
Main uses
- Research
Hazard
Compounds containing Protactinium
No compounds in this knowledge base contain Protactinium yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.