Protactinium |
| Symbol | Pa |
|---|---|
| Latin name | Protaktinium |
| Atomic number | 91 |
| Period | 7 |
| Element category | Inner transition elements |
| Relative atomic mass | 231.0359 |
| Group | V.B |
| Electronegativity | 1.5 |
| Oxidation numbers | 4, 5 |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 5f2 6d1 7s2 |
| Density [g/cm3] | 15.37 |
| State | Solid |
| Melting point [°C] | 1550 |
| Boiling point [°C] | 4225 |
| Thermal conductivity [W m-1K-1] | 47 |
| Discovery | 1917 |
| 1.st ionization energy [eV] | 5.89 |
| Stable isotopes | 0 |
| Unstable isotopes | 13 |