Atomic number: 72

Symbol: Hf

Category: transition metal

Density at 25°C: solid: density: 13.31 g·cm−3

Hafnium, the first transition metal after the lanthenoids, is quite corrosion resistant. It is mostly used in microchip electronics particularly in the 45nm range. The name hafnium is actually the latin name for what is now Copenhagen, the place where this element was discovered.

A bar of hafnium. image: adapted from wikipedia

Use, natural applications or common combinations: 

  • alloys, for example in rocket thrusters
  • lighting
  • hafnium oxides used in computer chip circuits at 45nm scale.
  • neutron absorber in nuclear reactors

Basic characteristics:

  • Standard atomic weight: 178.49(2)
  • Melting point:  2233 oC
  • Boiling point: 4603 °C
  • Radioactivity: most naturally stable
    • 182Hf (trace) half life 8.9×106 years via beta-
    • 174Hf (0.162%) half life of 2×1015 y via alpha. This is very slow and occasionally.