title: Mercury(I) iodide
text: Mercury(I) iodide, also known as mercurous iodide, is a chemical compound. Its chemical formula is Hg2I2. It has mercury and iodide ions in it. The mercury is in its +1 oxidation state.
  
  Properties
  It is a yellow solid. When light is shined on it, it breaks down (by disproportionation) to mercury(II) iodide and iodine. It is toxic, as are all mercury compounds.
  
  Preparation and use
  It is made by reacting mercury and iodine. It was once used as a medicine.
  
  Related pages
  Mercury(I) chloride
  Mercury(II) oxide
  Mercury(II) chloride
  
  Mercury compounds
  Iodine compounds