Periodic table of the elements
ThoriumProtactiniumUranium
91
Pa
Protactinium
231.03588
2
8
18
32
20
9
2
91
Pa
Protactinium
231.03588
2
8
18
32
20
9
2
General
NameProtactinium
SymbolPa
Number91
Chemical seriesActinides
Group / Period0 / 7
Blockf-block
CAS registry number7440-13-3

Protactinium is a radioactive element

Physical properties
Statesolid
Density15.37 g/cm3
Melting point1841 K (1568 °C, 2854 °F)
Boiling point4300 K (4027 °C, 7280.6 °F)
Critical point

Atomic properties
Atomic Weight231.03588 g/mol
Crystal structureorthorhombic
Electronegativity1.50
Atomic radius180 pm
Atomic radius (calculated)
Electron configuration[Rn] 7s2 6d1 5f2
Electrons per shell2, 8, 18, 32, 20, 9, 2
Number of protons91
Number of neutrons122

Other languages
SpanishProtactinio
PortugueseProtactí­nio
FrenchProtactinium
GermanProtactinium
ItalianProtoattinio
RussianПротактиний
PolishProtaktyn
Chinese
Arabicبروتكتينيوم
TurkishProtaktinyum
DutchProtactinium


Periodic table of the elements
ThoriumProtactiniumUranium