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 a color name in English was in 1805. "Avocado" is a color that is a representation of the color of the outer surface of an avocado. The color avocado is a dark yellow-green color. Avocado was a common color for metal surfaces (including automobiles and household appliances), as well as the color harvest gold, during the whole decade of the 1970s. They were both also popular colors for shag carpets. Both colors went out of style by the early 1980s. "Dark green" is a dark shade of green. A different shade of green has been designated as "dark green (X11)"