Hafnium

Hafnium (Hf)

Silvery lustrous metallic transition element. Used in tungsten alloys in filaments and electrodes, also acts as a neutron absorber. First reported by Urbain in 1911, existence was finally established in 1923 by D. Coster, G.C. de Hevesy in 1923.
Atomic Number72
Atomic Weight178.49
Mass Number180
Group4
Period6
Blockd
Protons72 p+
Neutrons108 n0
Electrons72 e-
Hf-crystal bar.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
155 pm
Atomic Volume
Covalent Radius
152 pm
Metallic Radius
144 pm
Ionic Radius
58 pm
Crystal Radius
72 pm
Van der Waals radius
223 pm
Density
13.3 g/cm³
Boiling Point
5,470 K
Melting Point
2,503 K
Electrons per shell2, 8, 18, 32, 10, 2
Electronegativity
1.3
Electrophilicity
0.8583981383413 eV/particle
Proton Affinity
Electron Affinity
Ionization Potential
6.82507 eV/particle
Heat of Vaporization
575 kJ/mol
Heat of Fusion
25.1 kJ/mol
Heat of Formation
618.4 kJ/mol
Molar Heat Capacity
25.73 J/(mol K)
Specific Heat Capacity
0.144 J/(g⋅K)
Thermal Conductivity
Gas Basicity
Dipole Polarizability
103 a₀
C6 Dispersion Coefficient
Oxidation States2, 3, 4
Color
Gray
Crystal StructureSimple Hexagonal (HEX)
Lattice Constant
3.2 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Xe] 4f14 5d2 6s2
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
CategoryTransition metals, Transition metals
CAS GroupIVA
IUPAC GroupIVB
Glawe Number50
Mendeleev Number45
Pettifor Number50
Geochemical Classhigh field strength
Goldschmidt Classlitophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
0.000007 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe7×10-8%

Isotopes of Hafnium

Stable Isotopes
174Hf 176Hf 177Hf 178Hf 179Hf 180Hf
Unstable Isotopes
153Hf 154Hf 155Hf 156Hf 157Hf 158Hf 159Hf 160Hf 161Hf 162Hf 163Hf 164Hf 165Hf 166Hf 167Hf 168Hf 169Hf 170Hf 171Hf 172Hf 173Hf 175Hf 181Hf 182Hf 183Hf 184Hf 185Hf 186Hf 187Hf 188Hf

History

In 1911, Georges Urbain claimed to have found the element in rare-earth residues which was shown later to be a mixture of already discovered lanthanides. Dirk Coster and George de Hevesy found it by X-ray spectroscopic analysis in Norwegian zircon in 1922. Anton Eduard van Arkel and Jan Hendrik de Boer were the first to prepare metallic hafnium by passing hafnium tetra-iodide vapor over a heated tungsten filament in 1924. From Hafinia, the Latin name for Copenhagen

DiscoverersDirk Coster, Georg von Hevesy
Discovery LocationDenmark
Discovery Year1923
Name OriginFrom Hafnia, the Latin name of Copenhagen.
Hafnium is considered to be non-toxic
In powdered form, hafnium is pyrophoric and can ignite spontaneously in air

Uses

Hafnium oxide-based compounds are being introduced into silicon-based chips to produce smaller, more energy efficient and performance packed processors. Most of the hafnium produced is used in the production of control rods for nuclear reactors. Hafnium is also used in photographic flash bulbs, light bulb filaments, and in electronic equipment as cathodes and capacitors. Used in reactor control rods because of its ability to absorb neutrons.

Sources

Obtained from mineral zircon or baddeleyite.