Calcium Calcium Calcium is a chemical element with symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The
Calcium chlorate Calcium chlorate Calcium chlorate is the calcium salt of chloric acid, with the chemical formula Ca(ClO). Like other chlorates, it is a strong oxidizer. Calcium chlorate is produced by passing chlorine gas through a hot suspension of calcium hydroxide in water, producing calcium hypochlorite, which disproportionates when heated with excess chlorine to give calcium chlorate and calcium chloride: This is also the first step of the Liebig process for the manufacture of potassium chlorate. In theory, electrolysis of hot calcium chloride solution will give chlorate, analogous to the process used for the manufacture of sodium chlorate. In practice, electrolysis is