Final answer:
The element in CFCs and HCFCs responsible for ozone depletion is chlorine. Chlorine atoms, released by UV radiation from these molecules, catalytically destroy ozone, decreasing the protective effect against harmful UV radiation.
Step-by-step explanation:
The element of a CFC (chlorofluorocarbon) or HCFC (hydrochlorofluorocarbon) molecule that causes ozone depletion is chlorine. Chlorine atoms are able to destroy large amounts of ozone in the stratosphere. Once released as a result of UV radiation breaking down CFCs, a single chlorine atom can catalytically decompose ozone molecules repeatedly. This reaction transforms triplet oxygen (O3) into ordinary diatomic oxygen (O2), thus reducing the ozone's capacity to absorb ultraviolet light and protect Earth's surface from harmful UV radiation.
CFCs and HCFCs have historically been used in products like refrigerants, air conditioning systems, foams, and aerosols. While CFCs are very stable and persist in the atmosphere, HCFCs break down more readily in the lower atmosphere, leading to less ozone-depleting potential. However, any chlorine released in the stratosphere from these substances is harmful to the ozone layer. This has prompted global efforts to replace CFCs and HCFCs with more environmentally benign substances.