Pa
Protactinium
Element 91 · Actinide · Period 7, Group 5
Solid · Discovered 1913
Atomic Properties
| Atomic Number | 91 |
| Atomic Mass | 231.03588u |
| Electron Configuration | [Rn]7s2 5f2 6d1 |
| Electronegativity | 1.5Pauling |
| Atomic Radius | 243pm |
| Ionization Energy | 5.89eV |
| Oxidation States | +5, +4 |
Physical Properties
| Standard State | Solid |
| Melting Point | 1845K |
| Density | 15.37g/cm³ |
| Group Block | Actinide |
| Year Discovered | 1913 |