 In addition, calcium chloride is widely used as a de-icer, since it is effective in lowering the melting point when applied to ice.Examples of covalently bonded chlorides are phosphorus trichloride, phosphorus pentachloride, and thionyl chloride, all three of which are reactive chlorinating reagents that have been used in a laboratory.Chlorine can assume oxidation states of −1, +1, +3, +5, or +7.