Physical and chemical properties

Aluminium is a soft, silvery light metal. It is very reactive so that in the atmosphere a thin but equally protective oxide layer forms rapidly. For this reason it is very resistant to corrosion. By a special treatment, anodizing, i. e. an electrolytic oxidation process, the aluminum surface protected by the oxide layer can even be strengthened and made more resistant to corrosion.
Aluminium reacts strongly with hydrochloric acid and caustic soda. The reaction with sulfuric acid is weaker, while it remains passive in contact with cold nitric acid.
Aluminium possesses good thermal and electrical conductivity, in each case about two-thirds of the values for pure copper. Due to its electronic configuration the element has three valency electrons; its oxidation number is therefore +3.


  • Melting point: 660 °C (for AL 99,99 acc. to composition / alloying higher resp. lower)
  • Boiling point: 2500 °C (acc. to composition / alloying higher resp. lower)
  • Density: 2,70 g/cm³
  • Relative atomic mass 26,98
  • Oxidation number: 3
  • Atomic radius: 143,1 pm
  • Ionic radius: 57 pm (+3)
  • Electrical conductivity: 36 m/Ohm·mm²

Portrait Alunorf

Alunorf - what we stand for

The biggest aluminum rolling and remelt plant in pictures. What we do, what we can do. /