Discovery date : 1774
Discovered by: Carl Wilhelm Scheele
Origin of the name: The name is derived from the Greek 'chloros', meaning greenish yellow.
Allotropes : Cl2
~>CHLORINE is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them.
| FACT BOX | |||
| Group | 17 | Melting point | −101.5°C, −150.7°F, 171.7 K |
| Period | 3 | Boiling point | −34.04°C, −29.27°F, 239.11 K |
| Block | p | Density (g cm−3) | 0.002898 |
| Atomic number | 17 | Relative atomic mass | 35.45 |
| State at 20°C | Gas | Key isotopes | 35Cl,37Cl |
| Electron configuration | [Ne] 3s23p5 | CAS number | 7782-50-5 |
| ChemSpider ID | 4514529 | ChemSpider is a free chemical structure database | |
Hydrochloric acid (HCl) was known to the alchemists. The gaseous element itself was first produced in 1774 by Carl Wilhelm Scheele at Uppsala, Sweden, by heating hydrochloric acid with the mineral pyrolusite which is naturally occuring manganese dioxide, MnO2. A dense, greenish-yellow gas was evolved which he recorded as having a choking smell and which dissolved in water to give an acid solution. He noted that it bleached litmus paper, and decolourised leaves and flowers.
Humphry Davy investigated it in 1807 and eventually concluded not only that it was a simple substance, but that it was truly an element. He announced this in 1810 and yet it took another ten years for some chemists finally to accept that chlorine really was an element.