Protactinium

Protactinium (Pa)

Protactinium is the 91st element in the periodic table and has a symbol of Pa and atomic number of 91. It has an atomic weight of (231.03588) and a mass number of 231. Protactinium has ninety-one protons and one hundred forty neutrons in its nucleus, and ninety-one electrons in seven shells. It is located in group Actinides, period seven and block f of the periodic table. 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-
Animated Bohr Model of Pa (Protactinium)

Physical 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
Atomic Radii of the Elements: Protactinium0255075100125150175200225250pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals Radius

Chemical Properties

Energy
Proton Affinity
Electron Affinity
Ionization Energy
Ionization Energies of Pa (Protactinium)
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
Bohr Model: Pa (Protactinium)
Valence Electrons2
Lewis Structure: Pa (Protactinium)
Electron Configuration[Rn] 5f2 6d1 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 5f2 6d1 7s2
Enhanced Bohr Model of Pa (Protactinium)
Orbital Diagram of Pa (Protactinium)
Oxidation States2, 3, 4, 5
Electronegativity
1.5
Electrophilicity Index
States of Matter
PhaseSolid
Gas Phase
Boiling Point
Melting Point
1,845.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual

Protactinium is a Silver. Pa has a CPK of #ffffff, Jmol of #00a1ff, and MOLCAS GV of #00a1ff. The Appearance of Element 91 is bright, silvery metallic luster.

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

The Crystal Structure of Protactinium is TET. The lattice constant of Pa is 3.92 Å. The lattice angles of Element 91 are π/2, π/2, π/2.

Crystal StructureCentered Tetragonal (TET)
Lattice Constant
3.92 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young's Modulus
Poisson Ratio
Speed of Sound
Classification

The Glawe Number of Protactinium is 35. The Mendeleev Number of Pa is 18. The Pettifor Number of Element 91 is 46. The Geochemical Class of Protactinium (Pa) is U/Th decay series. The Goldschmidt Class of Protactinium is litophile.

CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number35
Mendeleev Number18
Pettifor Number46
Geochemical ClassU/Th decay series
Goldschmidt Classlitophile

Other

The Dipole Polarizability of Protactinium is 154 plus or minus 20 a₀. The Allotropes of Pa is . The Neutron Cross Section of Element 91 is 200. The Quantum Numbers of Protactinium (Pa) is 4K11/2. The Space Group of Protactinium is 139 (I4/mmm).

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 Isotopes0
Unstable Isotopes31
Natural Isotopes1

211Pa

Mass Number211
Neutron Number120
Relative Atomic Mass
211.023674036 ± 0.000074581 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
6 ± 3 ms
Spin9/2
Quadrupole Moment
Discovery Year2006
Parity-

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

212Pa

Mass Number212
Neutron Number121
Relative Atomic Mass
212.023184819 ± 0.000094047 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5.8 ± 1.9 ms
Spin3
Quadrupole Moment
Discovery Year1997
Parity+

Decay ModeIntensity
α (α emission)100%

213Pa

Mass Number213
Neutron Number122
Relative Atomic Mass
213.021099644 ± 0.000061374 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
7.4 ± 2.4 ms
Spin9/2
Quadrupole Moment
Discovery Year1995
Parity-

Decay ModeIntensity
α (α emission)100%

214Pa

Mass Number214
Neutron Number123
Relative Atomic Mass
214.020891055 ± 0.00008718 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
17 ± 3 ms
Spin7
Quadrupole Moment
Discovery Year1995
Parity+

Decay ModeIntensity
α (α emission)100%

215Pa

Mass Number215
Neutron Number124
Relative Atomic Mass
215.019113955 ± 0.000088513 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
14 ± 2 ms
Spin9/2
Quadrupole Moment
Discovery Year1979
Parity-

Decay ModeIntensity
α (α emission)100%

216Pa

Mass Number216
Neutron Number125
Relative Atomic Mass
216.019134633 ± 0.000026459 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
105 ± 12 ms
Spin5
Quadrupole Moment
Discovery Year1972
Parity+

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

217Pa

Mass Number217
Neutron Number126
Relative Atomic Mass
217.018309024 ± 0.000013417 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
3.8 ± 0.2 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%
β (β decay)

218Pa

Mass Number218
Neutron Number127
Relative Atomic Mass
218.020021133 ± 0.000019158 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
108 ± 5 us
Spin8
Quadrupole Moment
Discovery Year1979
Parity-

Decay ModeIntensity
α (α emission)100%

219Pa

Mass Number219
Neutron Number128
Relative Atomic Mass
219.019949909 ± 0.000074831 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
56 ± 9 ns
Spin9/2
Quadrupole Moment
Discovery Year2005
Parity-

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

220Pa

Mass Number220
Neutron Number129
Relative Atomic Mass
220.021769753 ± 0.000015732 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
0.85 ± 0.06 us
Spin1
Quadrupole Moment
Discovery Year2005
Parity-

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

221Pa

Mass Number221
Neutron Number130
Relative Atomic Mass
221.021873393 ± 0.000063746 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5.9 ± 1.7 us
Spin9/2
Quadrupole Moment
Discovery Year1983
Parity-

Decay ModeIntensity
α (α emission)100%

222Pa

Mass Number222
Neutron Number131
Relative Atomic Mass
222.023687064 ± 0.000092975 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
3.8 ± 0.2 ms
Spin1
Quadrupole Moment
Discovery Year1970
Parity-

Decay ModeIntensity
α (α emission)100%

223Pa

Mass Number223
Neutron Number132
Relative Atomic Mass
223.023980414 ± 0.000081193 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5.3 ± 0.3 ms
Spin9/2
Quadrupole Moment
Discovery Year1970
Parity-

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

224Pa

Mass Number224
Neutron Number133
Relative Atomic Mass
224.025617286 ± 0.000008145 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
844 ± 19 ms
Spin5
Quadrupole Moment
Discovery Year1958
Parity-

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

225Pa

Mass Number225
Neutron Number134
Relative Atomic Mass
225.026147927 ± 0.000087887 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.71 ± 0.1 s
Spin5/2
Quadrupole Moment
Discovery Year1958
Parity-

Decay ModeIntensity
α (α emission)100%

226Pa

Mass Number226
Neutron Number135
Relative Atomic Mass
226.027948217 ± 0.000012037 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.8 ± 0.2 m
Spin1
Quadrupole Moment
Discovery Year1949
Parity-

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

227Pa

Mass Number227
Neutron Number136
Relative Atomic Mass
227.028803586 ± 0.000007797 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
38.3 ± 0.3 m
Spin5/2
Quadrupole Moment
Discovery Year1948
Parity-

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

228Pa

Mass Number228
Neutron Number137
Relative Atomic Mass
228.031050758 ± 0.000004659 Da
G-Factor
1.1666666666667 ± 0.16666666666667
Abundance
Radioactivity☢️ Radioactive
Half Life
22 ± 1 h
Spin3
Quadrupole Moment
Discovery Year1948
Parity+

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

229Pa

Mass Number229
Neutron Number138
Relative Atomic Mass
229.032095585 ± 0.000003521 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.55 ± 0.04 d
Spin5/2
Quadrupole Moment
Discovery Year1949
Parity+

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

230Pa

Mass Number230
Neutron Number139
Relative Atomic Mass
230.034539717 ± 0.000003261 Da
G-Factor
1 ± 0.1
Abundance
Radioactivity☢️ Radioactive
Half Life
17.4 ± 0.5 d
Spin2
Quadrupole Moment
Discovery Year1948
Parity-

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

231Pa

Mass Number231
Neutron Number140
Relative Atomic Mass
231.0358825 ± 0.000001901 Da
G-Factor
1.3266666666667 ± 0.013333333333333
Abundance
100
Radioactivity☢️ Radioactive
Half Life
32.65 ± 0.2 ky
Spin3/2
Quadrupole Moment
-1.72 ± 0.05
Discovery Year1918
Parity-

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

232Pa

Mass Number232
Neutron Number141
Relative Atomic Mass
232.038590205 ± 0.000008206 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.32 ± 0.02 d
Spin2
Quadrupole Moment
Discovery Year1949
Parity-

Decay ModeIntensity
β (β decay)100%
ϵ (electron capture)

233Pa

Mass Number233
Neutron Number142
Relative Atomic Mass
233.040246535 ± 0.000001433 Da
G-Factor
2.6666666666667 ± 0.46666666666667
Abundance
Radioactivity☢️ Radioactive
Half Life
26.975 ± 0.013 d
Spin3/2
Quadrupole Moment
-3 ± 0.4
Discovery Year1938
Parity-

Decay ModeIntensity
β (β decay)100%

234Pa

Mass Number234
Neutron Number143
Relative Atomic Mass
234.043305555 ± 0.000004395 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
6.7 ± 0.05 h
Spin4
Quadrupole Moment
Discovery Year1913
Parity+

Decay ModeIntensity
β (β decay)100%

235Pa

Mass Number235
Neutron Number144
Relative Atomic Mass
235.045399 ± 0.000015 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
24.4 ± 0.2 m
Spin3/2
Quadrupole Moment
Discovery Year1950
Parity-

Decay ModeIntensity
β (β decay)100%

236Pa

Mass Number236
Neutron Number145
Relative Atomic Mass
236.048668 ± 0.000015 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
9.1 ± 0.1 m
Spin1
Quadrupole Moment
Discovery Year1963
Parity

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

237Pa

Mass Number237
Neutron Number146
Relative Atomic Mass
237.051023 ± 0.000014 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
8.7 ± 0.2 m
Spin1/2
Quadrupole Moment
0
Discovery Year1954
Parity+

Decay ModeIntensity
β (β decay)100%

238Pa

Mass Number238
Neutron Number147
Relative Atomic Mass
238.054637 ± 0.000017 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
2.28 ± 0.09 m
Spin3
Quadrupole Moment
Discovery Year1968
Parity-

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

239Pa

Mass Number239
Neutron Number148
Relative Atomic Mass
239.05726 ± 0.00021 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.8 ± 0.5 h
Spin1/2
Quadrupole Moment
0
Discovery Year1995
Parity+

Decay ModeIntensity
β (β decay)100%

240Pa

Mass Number240
Neutron Number149
Relative Atomic Mass
240.061203 ± 0.000215 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin3
Quadrupole Moment
Discovery Year
Parity+

Decay ModeIntensity
β (β decay)

241Pa

Mass Number241
Neutron Number150
Relative Atomic Mass
241.064134 ± 0.000322 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year
Parity+

Decay ModeIntensity
β (β decay)
Protactinium-233

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
Natural Abundance (Oceans)
0.00000000005 mg/L
Natural Abundance (Human Body)
0 %
Natural Abundance (Meteor)
Natural Abundance (Sun)
Abundance in Universe
0 %

Nuclear Screening Constants

Also Known As

  • Pa
  • element 91
  • 91Pa
  • protoactinium
  • brevium

Translations

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  • Bosnianprotaktinij
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