Period 3 element in 1810, who named it chlorine, from the Greek word χλωρος (chlōros), meaning "green-yellow." Chlorine is a component of various compounds, including table salt. It is the second most abundant halogen and 21st most abundant chemical element in Earth's crust. The great oxidizing potential of chlorine led it to its bleaching and disinfectant uses, as well as uses of an essential reagent in the chemical industry. As a common disinfectant, chlorine compounds are used in swimming pools to keep them clean and sanitary. In the upper atmosphere, chlorine-containing molecules such as chlorofluorocarbons have been implicated in ozone depletion. "Argon" (symbol
Shades of green green" is a dark green color created by mixing Prussian blue and Gamboge. It is displayed on the right. Hooker's green takes its name from botanical artist William Hooker (1779–1832) who first created a special pigment for leaves. Displayed at right is the color "jungle green". In 1990, Crayola named and formulated this specific tone of jungle green. The first recorded use of "jungle green" as a name of a color in the English language was in 1926. "Laurel green" is a medium light hue of greenish gray similar to asparagus, but lighter. The first recorded use of "laurel green"