(So named (
Greek chloros, "pale green") for its color in
1810 by
Sir Humphry Davy, who proved it to be an element) A greenish-yellow,
poisonous,
gaseous
chemical element, one of the
halogens, having a disagreeable odor and obtained by
electrolysis of certain
chlorides. It is used as a
bleaching agent, in
water purification, in various industrial processes, etc.
Symbol: Cl
Atomic number: 17
Atomic weight: 35.4527
Density (at 0°C with 101,325 pascals): 3.214 g/L
Melting point: -101.5°C
Boiling point: -34.04°C
Valence: -1, +1, +3, +5, +7
Ground state electron configuration: [Ne]3s23p5