| Atomic Number: | 91 |
| Element Symbol: | Pa |
| Element Name: | Protactinium |
| Atomic Weight: | 231.03588 |
| Group Name: | Actinoid |
| Period Number: | 7 (actinoid) |
| Block: | f-block |
| Ground State Configuration: | [Rn] 5f2 6d 7s2 |
| Ground State Level: | 4K11/2 |
| Standard State: | Solid |
| Bond Length: | 321.2 |
| Atomic Radius Empirical: | 180 |
| First Ionization Energy: | 568 |
| Pauling Electronegativity: | 1.5 |
| Allred Rochow Electronegativity: | 1.14 |
| Density Of Solid: | 15370 |
| Molar Volume: | 15.18 |
| Electrical Resistivity: | 18 |
| Melting Point: | 1568 |
| Superconduction Temperature: | -271.7 |
| Thermal Conductivity: | 47 |
| Enthalpy Of Fusion: | 15 |
| Enthalpy Of Vaporization: | 470 |
| Enthalpy Of Atmization: | 607 |
| Most Common Oxidation Numbers: | 5 |
| Color: | Silvery metallic |
| Classification: | Metallic |
| Discovered By: | Otto Hahn, Lise Meitner, Frederick Soddy, John Cranston |
| Discovered At: | Germany, England |
| Discovered When: | 1913 |
| Origin Of Name: | From the Greek word protos meaning first |
Calculate the molecular weight of Protactinium or molecular weight Pa.
Also see the full list of chemical elements and atomic weights.