hafnium

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Most zirconium minerals contain 1 to 5% hafnium. Hafnium is a ductile metal with a brilliant silver lustre. Its properties are influenced considerably by the impurities of zirconium present. Of all the elements, zirconium and hafnium are two of the most difficult to separate. Hafnium is a Group 4 transition element.

Because hafnium has a good absorption cross section for thermal neutrons (almost 600 times that of zirconium), has excellent mechanical properties, and is extremely corrosion resistant, it is used for nuclear reactor control rods.

Hafnium carbide is the most refractory binary composition known, and the nitride is the most refractory of all known metal nitrides (m.p. 3310°C).

General information

Discoveror: Dirk Coster and George Charles von Hevesy
Date discovered: 1923
Discovered at: Denmark
Meaning of name: From the Latin word "Hafnia" meaning "Copenhagen"

Physical data

Standard state: solid at 298 K
Colour: grey steel
Density of solid at ambient temperature/kg m^-3: 13310
Molar volume/cm³: 13.44

Radii /pm

Atomic: 208
Covalent (single bond):
Pauling radius for the ion [Hf]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	177.9	no data	87.6	23.9

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.3
Allred Rochow: 1.23

Crystal Structure

structure: hcp (hexagonal close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 2506
boiling point: 4876

Enthalpies /kJ mol^-1

fusion: 25.0
vaporization: 626

single bond enthalpies:

Hf-F	Hf-Cl	Hf-Br	Hf-I	Hf-Hf
no data	no data	no data	no data	no data

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	654
2nd	1440
3rd	2250
4th	3210
5th	6600

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
174Hf	173.940044 (4)	0.162 (3)
176Hf	175.941406 (4)	5.206 (5)
177Hf	176.943217 (3)	18.606 (4)
178Hf	177.943696 (3)	27.297 (4)
179Hf	178.9458122 (29)	13.629 (6)
180Hf	179.9465457 (30)	35.100 (7)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW