de en fr hr it es
Neighborhood
Y
39
Zr
40
Nb
41
Lu
71
Hf
72
Ta
73
Lr
103
Rf
104
Db
105

 

Periodic table

de  German

Hafnium

en  English

Hafnium

fr  French

Hafnium

hr  Croatian

Hafnij

it  Italian

Afnio

es  Spanish

Hafnio

 

Hf
Hf
Hafnium

PERIODIC TABLE OF THE ELEMENTS

HAFNIUM

TRANSITION ELEMENT: TITANIUM GROUP

 

Atomic number:72

Group numbers:4

Period:6

Electronic configuration:[Xe] 4f14 5d2 6s2

Formal oxidation number:+4

Electronegativities:1.3

Atomic radius / pm:156.4

Relative atomic mass:178.49 ± 0.02

 

Hafnium was discovered by Dirk Coster (NL) and George Charles von Hevesy (HU) in 1923. The origin of the name comes from the Latin name Hafnia meaning Copenhagen. It is a silvery, ductile, toxic metal that resists alkalis and acids (except HF). Metal ignites and burns readily and the exposed surfaces form oxide film. Hafnium is obtained from mineral zircon or baddeleyite. It is used in reactor control rods because of its ability to absorb neutrons.

PHYSICAL PROPERTIES

Density / g dm-3:13310 (293 K)

 12000 (m.p.)

Molar volume / cm3mol-1:13.41 (293 K)

 14.87 (m.p.)

Electrical resistivity / μΩcm:33.08 (20 °C)

THERMAL PROPERTIES

Thermal conductivity / W m-1K-1:23

Melting point / °C:2233

Boiling point / °C:4603

Heat of fusion / kJ mol-1:25.5

Heat of vaporization / kJ mol-1:570.7

Heat of atomization / kJ mol-1:618.9

IONIZATION ENERGIES

First ionization energy / kJ mol-1:658.52

Second ionization energy / kJ mol-1:1437.64

Third ionization energy / kJ mol-1:2248.12

ABUNDANCE OF ELEMENTS

in the atmosphere / ppm:-

in the Earth's crust / ppm:3

in the oceans / ppm:0.008

CRYSTALLOGRAPHIC DATA

hexagonal

Crystal structure:

hexagonal

Unit-cell dimensions / pm:

a=319.46, c=505.10

Space group:

P63/mmc

ISOTOPES

IsotopeRelative atomic massMass percent (%)
174Hf173.940040(3)0.162(3)
176Hf175.941402(3)5.206(5)
177Hf176.943220(3)18.606(4)
178Hf177.943698(3)27.297(4)
179Hf178.945815(3)13.629(6)
180Hf179.946549(3)35.100(7)

REDUCTION POTENTIALS

Balanced half-reaction Eo / V
Hf4+ + 4e- = Hf(s)- 1.70
HfO2(s) + 4H+ + 4e- = Hf(s) + 2H2O- 1.57
HfO2+ + 2H+ + 4e- = Hf(s) + H2O- 1.70
HfO(OH)2(s) + H2O + 4e- = Hf(s) + 4OH-- 2.50

 

71 Lutetium <=
72 Hafnium
 => 73 Tantalum