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 for certain computer uses. "Fern green" is a color that resembles ferns. A Crayola crayon named "fern" was created in 1998, which is a lighter shade of the top color shown on the right. The first recorded use of "fern green" as a color name in English was in 1902. "Forest green" refers to a green color said to resemble the color of the trees and other plants in a forest. The first recorded use of "forest green" as the name of a color in the English language was in 1810. Displayed at right is the color "green earth". "Hooker's