Atomic number 91
Protactinium
Actinide
Quick facts
- Atomic mass
- 231.04
- Group
- —
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 1.50
- Common ox. states
- +4, +5
Properties
Electron configuration
[Rn] 5f² 6d¹ 7s²
- Ionization energy
- 568.0 kJ/mol
- Electron affinity
- —
- Melting point
- 1845.00 K (1571.8 °C)
- Boiling point
- 4300.00 K (4026.8 °C)
How it bonds· family overview
Protactinium (Pa) is an actinide. Like the lanthanides it tends toward a +3 oxidation state, but the early actinides (Th–Am) routinely access +4, +5, +6, even +7 because the 5f electrons are easier to ionize. Most actinides are radioactive; their "bonding" in school is read off the periodic table, not measured in lab.