Calcium iodide is an inorganic compound with the molecular formula CaI2, explains World of Chemicals. CaI2 is composed of a central calcium ion ionically bound to two iodine ions, with a linear molecular geometry. The single calcium ion has a 2+ charge, while each iodine ion has a 1- charge.
Calcium iodide is a white, solid powder that is highly soluble in water. Calcium iodide slowly reacts with oxygen and carbon dioxide in the air, which releases the iodine ions and forms calcium carbonate. A yellowish change in color indicates a decomposition, as the yellow hue is caused by the separating iodine ions. Calcium iodide can also be formed through the interaction of calcium carbonate with hydroiodic acid.