Name: Protactinium
Symbol: Pa
Atomic Number: 91
AtomicWeight: 231.035880
Family: Actinides
CAS RN: 7440-13-3
Description: A silvery metallic metal, highly toxic and radioactive
State (25 °C): Solid
Melting Point: 1841 °K
Boiling Point: 4300 °K
Density: 15.37 g/cm³
Oxidation states: +5,+4
Electron Configuration: [Rn] 5f²6d¹7s²
Radius: 180 pm (Covalent)
Electronegativity: 1.5 (Pauling Scale)

1st Ionization Energy: 568 KJ/mole
2nd Ionization Energy: 1128 KJ/mole
3rd Ionization Energy: 1814 KJ/mole