Hafnium ) is a chemical element with the symbolHf and atomic number 72. A lustrous, silvery gray, tetravalenttransition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable isotope element to be discovered (rhenium was identified two years later). Hafnium is named for Hafnia, the Latin name for "Copenhagen", where it was discovered.

Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.

Hafnium's large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.

General Properties  for Hafnium:

• Symbol                 Hf
  
• Atomic Number     72
  
• Atomic Weight:     178.49
• Density (near r.t):  13.31 g.cm⁻³
• Liquid density at m.p:      12g.cm⁻³
  Melting Point:        2233°C
• Boiling Point:         4603°C