Arsenic (As)
Arsenic (As) is element 33, a metalloid. Atomic mass 74.921595, configuration [Ar] 3d¹⁰ 4s² 4p³. Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 33 |
|---|---|
| Symbol | As |
| Standard atomic weight | 74.921595(6) |
| Category | Metalloid |
| Group | 15 |
| Period | 4 |
| State at room temperature | Solid |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p³ |
| Valence electrons | 5 |
| Common oxidation states | -3, +3, +5 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 2.18 |
| First ionization energy | 947 kJ/mol |
| Electron affinity | 77.57 kJ/mol |
| Atomic radius | 114 pm |
| Density | 5.75 g/cm³ |
| Melting point | Sublimes |
| Boiling point | Sublimes |
| Specific heat | 0.329 J/(g·°C) |
Natural isotopes
- As-75: Stable
Common uses
- Semiconductors (GaAs)
- Wood preservatives (historical)
- Alloys
Where it matters
- Toxicology (Historical poison)
- Semiconductor doping (n-type)
Hazards
- Highly toxic
- Carcinogenic
History
| Discovered | ~1250 (Isolated) |
|---|---|
| Discovered by | Albertus Magnus (attributed) |
| Name | From Persian zarnikh (yellow orpiment) |