Arsenic
Metalloid
Arsenic (As) is a chemical element with atomic number 33, classified as a metalloid. At room temperature it is a solid. It was discovered in 1250 by Albertus Magnus.
Properties
- Atomic number
- 33
- Atomic mass
- 74.922 u
- Category
- Metalloid
- Group
- 15
- Period
- 4
- Block
- p-block
- Electron configuration
- [Ar] 3d¹⁰ 4s² 4p³
- Phase at STP
- Solid
- Density
- 5.776 g/cm³
- Melting point
- 1090 K (816.9 °C)
- Boiling point
- 887 K (613.9 °C)
- Electronegativity
- 2.18
- Atomic radius
- 114 pm
- Ionization energy
- 9.815 eV
- Discovery
- 1250 · Albertus Magnus
Common uses
Wood preservatives, semiconductors, pesticides, alloys
Did you know?
Notorious poison but also used in life-saving cancer treatments.
Experiment with the elements
Arsenic doesn't form any compounds in our lab yet, but the periodic table sandbox lets you combine dozens of other real elements into real compounds — water, table salt, ammonia and many more — with their true chemical formulas.