Any of the five chemical elements in Group 17 of the periodic table: fluorine, chlorine, bromine, iodine, and astatine. These elements readily form salts when combined with metals.
Coined in 1842 by Swedish chemist Jöns Jacob Berzelius from Greek 'halos' (salt) and 'genes' (born or produced), literally meaning 'salt-producer.' This describes their property of forming salts when they react with metals.
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