91
Pa
protactinium
231.04

General properties

Group
n/a
Period
period 7
Category
actinoids
Standard atomic weight
231.035 88(1)
Melting point
1841 K (1568 °C)
Boiling point
4300 K (4027 °C)
Phase at STP
solid

Additional properties

Block
f-block
Electron configuration
[Rn] 5f² 6d¹ 7s²
Electrons per shell
2, 8, 18, 32, 20, 9, 2
Electronegativity
1.5
Density
15.37 g/cm³
Oxidation states
+2, +3, +4, +5 (a weakly basic oxide)
CAS Number
7440-13-3