Protactinium

Protactinium (Pa)

Radioactive metallic element, belongs to the actinoids. The most stable isotope, Pa-231 has a half-life of 2.43*10^4 years. At least 10 other radioactive isotopes are known. No practical applications are known. Discovered in 1917 by Lise Meitner and Otto Hahn.
Atomic Number91
Atomic Weight231.03588
Mass Number231
Group
Period7
Blockf
Protons91 p+
Neutrons140 n0
Electrons91 e-
Protactinium-233.jpg Animated Bohr Model of Pa (Protactinium) Enhanced Bohr Model of Pa (Protactinium) Bohr Model: Pa (Protactinium) Orbital Diagram of Pa (Protactinium)

Properties

Atomic Radius
180 pm
Molar Volume
Covalent Radius
169 pm
Metallic Radius
Ionic Radius
104 pm
Crystal Radius
118 pm
Van der Waals Radius
243 pm
Density
15.4 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
Heat of Vaporization
481.2 kJ/mol
Heat of Fusion
16.7 kJ/mol
Heat of Formation
563 kJ/mol
Electrons
Electron Shells2, 8, 18, 32, 20, 9, 2
Valence Electrons5
Electron Configuration[Rn] 5f2 6d1 7s2
Oxidation States2, 3, 4, 5
Electronegativity
1.5
Electrophilicity
Phases
PhaseSolid
Gas Phase
Boiling Point
Melting Point
1,845.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearancebright, silvery metallic luster
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
5.6 MS/m
Electrical Resistivity
0.00000018 m Ω
Superconducting Point
1.41 K
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.0000000325 m³/Kg
Magnetic Susceptibility (Molar)
0.000000007509 m³/mol
Magnetic Susceptibility (Volume)
0.0004995
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureCentered Tetragonal (TET)
Lattice Constant
3.92 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
Classification
CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number35
Mendeleev Number18
Pettifor Number46
Geochemical ClassU/Th decay series
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
154 ± 20 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
200
Neutron Mass Absorption
Quantum Numbers4K11/2
Space Group139 (I4/mmm)

Isotopes of Protactinium

Stable Isotopes1
Unstable Isotopes30
Radioactive Isotopes31

211Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
211.023674036 ± 0.000074581 Da
Mass Number211
G-Factor
Half Life
6 ± 3 ms
Spin9/2
Quadrupole Moment
Discovery Year2006
Parity-

211Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%
p (proton emission)%

212Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
212.023184819 ± 0.000094047 Da
Mass Number212
G-Factor
Half Life
5.8 ± 1.9 ms
Spin3
Quadrupole Moment
Discovery Year1997
Parity+

212Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

213Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
213.021099644 ± 0.000061374 Da
Mass Number213
G-Factor
Half Life
7.4 ± 2.4 ms
Spin9/2
Quadrupole Moment
Discovery Year1995
Parity-

213Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

214Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
214.020891055 ± 0.00008718 Da
Mass Number214
G-Factor
Half Life
17 ± 3 ms
Spin7
Quadrupole Moment
Discovery Year1995
Parity+

214Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

215Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
215.019113955 ± 0.000088513 Da
Mass Number215
G-Factor
Half Life
14 ± 2 ms
Spin9/2
Quadrupole Moment
Discovery Year1979
Parity-

215Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

216Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
216.019134633 ± 0.000026459 Da
Mass Number216
G-Factor
Half Life
105 ± 12 ms
Spin5
Quadrupole Moment
Discovery Year1972
Parity+

216Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%

217Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
217.018309024 ± 0.000013417 Da
Mass Number217
G-Factor
Half Life
3.8 ± 0.2 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

217Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β (β decay)%

218Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
218.020021133 ± 0.000019158 Da
Mass Number218
G-Factor
Half Life
108 ± 5 us
Spin8
Quadrupole Moment
Discovery Year1979
Parity-

218Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

219Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
219.019949909 ± 0.000074831 Da
Mass Number219
G-Factor
Half Life
56 ± 9 ns
Spin9/2
Quadrupole Moment
Discovery Year2005
Parity-

219Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%

220Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
220.021769753 ± 0.000015732 Da
Mass Number220
G-Factor
Half Life
0.85 ± 0.06 us
Spin1
Quadrupole Moment
Discovery Year2005
Parity-

220Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%

221Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
221.021873393 ± 0.000063746 Da
Mass Number221
G-Factor
Half Life
5.9 ± 1.7 us
Spin9/2
Quadrupole Moment
Discovery Year1983
Parity-

221Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

222Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
222.023687064 ± 0.000092975 Da
Mass Number222
G-Factor
Half Life
3.8 ± 0.2 ms
Spin1
Quadrupole Moment
Discovery Year1970
Parity-

222Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

223Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
223.023980414 ± 0.000081193 Da
Mass Number223
G-Factor
Half Life
5.3 ± 0.3 ms
Spin9/2
Quadrupole Moment
Discovery Year1970
Parity-

223Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%

224Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
224.025617286 ± 0.000008145 Da
Mass Number224
G-Factor
Half Life
844 ± 19 ms
Spin5
Quadrupole Moment
Discovery Year1958
Parity-

224Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)%

225Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
225.026147927 ± 0.000087887 Da
Mass Number225
G-Factor
Half Life
1.71 ± 0.1 s
Spin5/2
Quadrupole Moment
Discovery Year1958
Parity-

225Pa Decay Modes
Decay ModeIntensity
α (α emission)100%

226Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
226.027948217 ± 0.000012037 Da
Mass Number226
G-Factor
Half Life
1.8 ± 0.2 m
Spin1
Quadrupole Moment
Discovery Year1949
Parity-

226Pa Decay Modes
Decay ModeIntensity
α (α emission)74%
β+ (β+ decay; β+ = ϵ + e+)26%

227Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
227.028803586 ± 0.000007797 Da
Mass Number227
G-Factor
Half Life
38.3 ± 0.3 m
Spin5/2
Quadrupole Moment
Discovery Year1948
Parity-

227Pa Decay Modes
Decay ModeIntensity
α (α emission)85%
ϵ (electron capture)15%

228Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
228.031050758 ± 0.000004659 Da
Mass Number228
G-Factor
1.1666666666667 ± 0.16666666666667
Half Life
22 ± 1 h
Spin3
Quadrupole Moment
Discovery Year1948
Parity+

228Pa Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)98.15%
α (α emission)1.85%

229Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
229.032095585 ± 0.000003521 Da
Mass Number229
G-Factor
Half Life
1.55 ± 0.04 d
Spin5/2
Quadrupole Moment
Discovery Year1949
Parity+

229Pa Decay Modes
Decay ModeIntensity
ϵ (electron capture)99.51%
α (α emission)0.49%

230Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
230.034539717 ± 0.000003261 Da
Mass Number230
G-Factor
1 ± 0.1
Half Life
17.4 ± 0.5 d
Spin2
Quadrupole Moment
Discovery Year1948
Parity-

230Pa Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)92.2%
β (β decay)7.8%
α (α emission)0.0032%

231Pa

AbundanceRadioactive ☢️
100
Relative Atomic Mass
231.0358825 ± 0.000001901 Da
Mass Number231
G-Factor
1.3266666666667 ± 0.013333333333333
Half Life
32.65 ± 0.2 ky
Spin3/2
Quadrupole Moment
-1.72 ± 0.05
Discovery Year1918
Parity-

231Pa Decay Modes
Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)3%
24Ne (heavy cluster emission)13.4%
23F9.9%

232Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
232.038590205 ± 0.000008206 Da
Mass Number232
G-Factor
Half Life
1.32 ± 0.02 d
Spin2
Quadrupole Moment
Discovery Year1949
Parity-

232Pa Decay Modes
Decay ModeIntensity
β (β decay)100%
ϵ (electron capture)%

233Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
233.040246535 ± 0.000001433 Da
Mass Number233
G-Factor
2.6666666666667 ± 0.46666666666667
Half Life
26.975 ± 0.013 d
Spin3/2
Quadrupole Moment
-3 ± 0.4
Discovery Year1938
Parity-

233Pa Decay Modes
Decay ModeIntensity
β (β decay)100%

234Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
234.043305555 ± 0.000004395 Da
Mass Number234
G-Factor
Half Life
6.7 ± 0.05 h
Spin4
Quadrupole Moment
Discovery Year1913
Parity+

234Pa Decay Modes
Decay ModeIntensity
β (β decay)100%

235Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
235.045399 ± 0.000015 Da
Mass Number235
G-Factor
Half Life
24.4 ± 0.2 m
Spin3/2
Quadrupole Moment
Discovery Year1950
Parity-

235Pa Decay Modes
Decay ModeIntensity
β (β decay)100%

236Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
236.048668 ± 0.000015 Da
Mass Number236
G-Factor
Half Life
9.1 ± 0.1 m
Spin1
Quadrupole Moment
Discovery Year1963
Parity

236Pa Decay Modes
Decay ModeIntensity
β (β decay)100%
β SF (β-delayed fission)6%

237Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
237.051023 ± 0.000014 Da
Mass Number237
G-Factor
Half Life
8.7 ± 0.2 m
Spin1/2
Quadrupole Moment
0
Discovery Year1954
Parity+

237Pa Decay Modes
Decay ModeIntensity
β (β decay)100%

238Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
238.054637 ± 0.000017 Da
Mass Number238
G-Factor
Half Life
2.28 ± 0.09 m
Spin3
Quadrupole Moment
Discovery Year1968
Parity-

238Pa Decay Modes
Decay ModeIntensity
β (β decay)100%
β SF (β-delayed fission)2.6%

239Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
239.05726 ± 0.00021 Da
Mass Number239
G-Factor
Half Life
1.8 ± 0.5 h
Spin1/2
Quadrupole Moment
0
Discovery Year1995
Parity+

239Pa Decay Modes
Decay ModeIntensity
β (β decay)100%

240Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
240.061203 ± 0.000215 Da
Mass Number240
G-Factor
Half Life
Spin3
Quadrupole Moment
Discovery Year
Parity+

240Pa Decay Modes
Decay ModeIntensity
β (β decay)%

241Pa

AbundanceRadioactive ☢️
Relative Atomic Mass
241.064134 ± 0.000322 Da
Mass Number241
G-Factor
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year
Parity+

241Pa Decay Modes
Decay ModeIntensity
β (β decay)%

History

In 1900, William Crookes isolated protactinium as an intensely radioactive material from uranium Protactinium was first identified in 1913 by Kasimir Fajans and Oswald Helmuth Göhring in Germany. A more stable isotope of protactinium was discovered in 1917 by Otto Hahn and Lise Meitner at the Kaiser Wilhelm Institute in Berlin. From the Greek protos meaning first

DiscoverersFredrich Soddy, John Cranston, Otto Hahn, Lise Meitner
Discovery LocationEngland/France
Discovery Year1917
Etymology (Name Origin)Greek: proto and actinium (parent of actinium); it forms actinium when it radioactively decays.
PronunciationPRO-tak-tin-eh-em (English)
Protactinium is toxic and highly radioactive
Protactinium is one of the rarest and most expensive naturally occurring elements

Uses

Owing to its scarcity, high radioactivity and high toxicity, there are currently no uses for protactinium outside of scientific research. With the advent of highly sensitive mass spectrometers, an application of 231Pa as a tracer in geology and paleoceanography has become possible. Protactinium-231 combined with the thorium-230 can be used to date marine sediments. It has no significant commercial applications.

Sources

Does not occur in nature. Found among fission products of uranium, thorium, and plutonium.

Abundance
Abundance in Earth's crust
0.0000014 mg/kg
Abundance in Oceans
0.00000000005 mg/L
Abundance in Human Body
0 %
Abundance in Meteor
Abundance in Sun
Abundance in Universe
0 %

Nuclear Screening Constants