Discovery date : 1798
Discovered by:Nicholas Louis Vauquelin
Origin of the name: The name is derived from the Greek 'chroma', meaning colour.
Allotropes :
~>CHROMIUM is a chemical element with symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
| FACT BOX | |||
| Group | 6 | Melting point | 1907°C, 3465°F, 2180 K |
| Period | 4 | Boiling point | 2671°C, 4840°F, 2944 K |
| Block | d | Density (g cm−3) | 7.15 |
| Atomic number | 24 | Relative atomic mass | 51.996 |
| State at 20°C | Solid | Key isotopes | 52Cr |
| Electron configuration | [Ar] 3d54s1 | CAS number | 7440-47-3 |
| ChemSpider ID | 22412 | ChemSpider is a free chemical structure database | |
Chromium was discovered by the French chemist Nicholas Louis Vauquelin at Paris in1798. He was intrigued by a bright red mineral that had been discovered in a Siberian gold mine in 1766 and was referred to as Siberian red lead. It is now known as crocoite and is a form of lead chromate. Vauquelin analysed it and confirmed that it was a lead mineral. Then he dissolved it in acid, precipitated the lead, filtered this off, and focused his attention on the remaining liquor from which he succeeded in isolating chromium. Intrigued by the range of colours that it could produce in solution, he named it chromium from the Greek word chroma meaning colour. He then discovered that the green colouration of emeralds was also due to chromium.