How does the highly reactive nature chlorine contribute to the creation of ozone holes in the upper atmosphere?

Chlorine is a halogen and is very reactive and unstable. If released in an elemental form (Cl2), it would react with other substances immediately. However, chlorofluorocarbons (CFCs) which contain chlorine are unreactive and when released they eventually end up in the upper atmosphere still "intact". In the upper atmosphere, sunlight is more intense and is able to break apart CFC, releasing the highly reactive chlorine which in turns destroys ozone which is more abundant in the upper atmosphere (stratosphere).