Discovery date : approx 1250
Discovered by: Albertus Magnus
Origin of the name: The name is thought to come from 'arsenikon',
the Greek name for the yellow pigment orpiment.
Allotropes : Yellow As, Grey As, Black As
~>ARSENIC is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid.
| FACT BOX | |||
| Group | 15 | Melting point | Sublimes at 616°C, 1141°F, 889 K |
| Period | 4 | Boiling point | Sublimes at 616°C, 1141°F, 889 K |
| Block | d | Density (g cm−3) | 5.75 |
| Atomic number | 33 | Relative atomic mass | 74.922 |
| State at 20°C | Solid | Key isotopes | 75As |
| Electron configuration | [Ar] 3d104s24p3 | CAS number | 7440-38-2 |
| ChemSpider ID | 4514330 | ChemSpider is a free chemical structure database | |
Arsenic was known to the ancient Egyptian, and is mentioned in one papyrus as a ways of gilding metals. The Greek philosopher Theophrastus knew of two arsenic sulfide minerals: orpiment (As2S3) and realgar (As4S4). The Chinese also knew about arsenic as the writings of Pen Ts’ao Kan-Mu. He compiled his great work on the natural world in the 1500s, during the Ming dynasty. He noted the toxicity associated with arsenic compounds and mentioned their use as pesticides in rice fields.
A more dangerous form of arsenic, called white arsenic, has also been long known. This was the trioxide, As2O3, and was a by-product of copper refining. When this was mixed with olive oil and heated it yielded arsenic metal itself. The discovery of the element arsenic is attributed to Albertus Magnus in the 1200s.