Sodium: sodium iodide

sodium iodide is known by the following synonyms:

  • sodium iodide
  • sodium(I) iodide

The oxidation number of sodium in sodium iodide is 1.

  • Formula: NaI
  • Hill system formula: I1Na1
  • CAS registry number: [7681-82-5]
  • Formula weight: 149.894
  • Class: iodide
  • Colour: white
  • Appearance: crystalline solid
  • Melting point: 660°C
  • Boiling point: 1304°C
  • Density: 3670 °C

Synthesis

One way to make sodium iodide is to react the hydroxide with hydroiodic acid. The resulting salt can then be purified by recrystallization.

NaOH(aq) + HI(aq) → NaI(aq) + H2O(l)

While not a normal route of preparation because of the expense, sodium metal reacts vigorously with all the halogens to form sodium halides. So, it burns with iodine, I2, to form sodium(I) iodide, NaI.

2Na(s) + I2(s) → 2NaI(s)

Solid state structure

  • Geometry of sodium: 6 coordinate: octahedral
  • Prototypical structure: NaCl (rock salt)

Crystal structure of sodium iodide

Element analysis

Element percentages in sodium iodide
Element %
I 84.66
Na 15.34

Isotope pattern for NaI

THe chart below shows the calculated isotope pattern for the formula NaI with the most intense ion set to 100%.

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References

The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

  • R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
  • N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
  • A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
  • R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
  • A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
  • A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
  • J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
  • D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
  • J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
  • J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.

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