Symbol
Pa
Atomic Number
91
Atomic Mass
231.03588
Protons
91
Neutrons
140
Electrons
91
Type
Actinide
Isotopes
Protactinium-231
Discovery Year
1913
Discovered By
Otto Hahn, Lise Meitner
Group
3
Period
7
Boiling Point
3877°F
Melting Point
1562°F
Electron Configuration
[Rn] 7s² 6d³
Density (g/cm³)
15.37
Crystal Structure
Orthorhombic
Magnetism
Paramagnetic
Abundance in Earth's Crust
0.0008%
Phase at Room Temperature
Solid