Periodic Table of the Elements
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Bottom FACULTY OF CHEMICAL TECHNOLOGY o PERIODIC TABLE OF THE ELEMENTS Bottom
  A B C D E F G H I J K L M N O P R S T U V X Z  
Periodic Table of the Elements Tableau périodique des éléments Periodni sustav elemenata Tavola periodica degli elementi Das Periodensystem der Elemente
Hafnium Hafnium Hafnij Afnio Hafnium

 
Atomic number: 72
Group numbers: 4
Period: 6
 
Discovery date: 1923
Hf

Hafnium
NEIGHBOURS
39
Y
 40
Zr
 41
Nb
71
Lu
 72
Hf
 73
Ta
103
Lr
 104
Rf
 105
Db


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Hafnium was discovered by Dirk Coster (Denmark) and Georg Karl von Hevesy (Hungary) in 1923. The origin of the name comes from the Latin name Hafnia meaning Copenhagen. It is silvery, ductile metal. Exposed surfaces form oxide film. Resists alkalis and acids (except HF). Toxic. Metal ignites and burns readily.
Bottom TRANSITION ELEMENT: TITANIUM GROUP Top

Relative atomic mass: 178.49(2) Electronic configuration: [Xe] 4f14 5d2 6s2
Formal oxidation number: +4 Electronegativities: 1.3
Thermal conductivity: 23 W m-1 K-1 Electrical resistivity (20 °C): 33.08 μΩcm
Atomic radius: 156.4 pm Standard state (20 °C): solid
Density (g dm-3): 13310 (293 K)
12000 (m.p.)		 Molar volume (cm3 mol-1): 13.41 (293 K)
14.87 (m.p.)


Bottom THERMAL PROPERTIES Top

Melting point: 2233 °C Heat of fusion: 25.5 kJ mol-1
Boiling point: 4603 °C Heat of vaporization: 570.7 kJ mol-1
Critical temperature: 10127 °C Heat of atomization: 618.9 kJ mol-1


Bottom IONIZATION ENERGIES AND ABUNDANCE Top

1st ionization energy: 658.52 kJ mol-1 Abundance of element (air): - ppm
2nd ionization energy: 1437.64 kJ mol-1 Abundance of element (Earth's crust): 3 ppm
3rd ionization energy: 2248.12 kJ mol-1 Abundance of element (oceans): 0.008 ppm


Bottom ISOTOPES Top

Isotopes Relative atomic mass Abundance (%)
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)


Bottom MINERALS AND USES Top

Hafnium is obtained from mineral zircon or baddeleyite. Used in reactor control rods because of its ability to absorb neutrons. The price of 99.9 % pure hafnium pieces is 260.60 € for 50 g.

Bottom REDUCTION POTENTIALS Top

Balanced half-reaction   Eo / V      Annotation
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  

 

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