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 Number212
Group
Period7
Blockf
Protons91 p+
Neutrons121 n0
Electrons91 e-
Protactinium-233.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
180 pm
Atomic Volume
Covalent Radius
169 pm
Metallic Radius
Ionic Radius
104 pm
Crystal Radius
118 pm
Van der Waals radius
243.00000000000003 pm
Density
15.4 g/cm³
Boiling Point
4,300 K
Melting Point
2,113 K
Electrons per shell2, 8, 18, 32, 20, 9, 2
Electronegativity
1.5
Electrophilicity
Proton Affinity
Electron Affinity
Ionization Potential
Heat of Vaporization
481.2 kJ/mol
Heat of Fusion
16.7 kJ/mol
Heat of Formation
563 kJ/mol
Molar Heat Capacity
Specific Heat Capacity
Thermal Conductivity
Gas Basicity
Dipole Polarizability
154 a₀
C6 Dispersion Coefficient
Oxidation States3, 4, 5
Color
Silver
Crystal StructureCentered Tetragonal (TET)
Lattice Constant
3.92 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Rn] 5f2 6d1 7s2
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number35
Mendeleev Number18
Pettifor Number46
Geochemical ClassU/Th decay series
Goldschmidt Classlitophile
Radioactivity
RadioactiveYes ☢️
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
0.0000014 mg/kg
Abundance in Oceans
0.00000000005 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universena

Isotopes of Protactinium

Stable Isotopes
Unstable Isotopes
212Pa 213Pa 214Pa 215Pa 216Pa 217Pa 218Pa 219Pa 220Pa 221Pa 222Pa 223Pa 224Pa 225Pa 226Pa 227Pa 228Pa 229Pa 230Pa 231Pa 232Pa 233Pa 234Pa 235Pa 236Pa 237Pa 238Pa 239Pa 240Pa

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
Name OriginGreek: proto and actinium (parent of actinium); it forms actinium when it radioactively decays.
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.