Arsenic (As)
Arsenicum
Arsenic (As) is a metalloid in period 4, group 15. Its relative atomic mass is 74.922 and the molar mass of the atom is 74.922 g/mol.
Atomic number 33
Atomic mass 74.922
Molar mass 74.922 g/mol
Category Metalloid Solid
Properties of arsenic
| Atomic number | 33 |
|---|---|
| Symbol | As |
| Latin name | Arsenicum |
| Relative atomic mass | 74.922 |
| Molar mass | 74.922 g/mol |
| Group, period, block | 15, 4, p |
| Category | Metalloid |
| State at 20 °C | Solid |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p³ |
| Electronegativity (Pauling) | 2.18 |
| Atomic radius | 115 pm |
Electron configuration of arsenic
Electrons per shell
K2L8M18N5
Full notation
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³
Noble-gas notation
33 protons · 33 electrons[Ar] 3d¹⁰ 4s² 4p³
Formula and compounds of arsenic
Simple substanceAsarsenicMolar mass of As: 74.922 g/mol
Chemistry not clicking? Try a lesson with a tutor
1-to-1 online chemistry lessons for KS3, GCSE and A-level. Your first lesson is a free trial.
Frequently asked questions
The relative atomic mass of arsenic is 74.922, so the molar mass of the atom is 74.922 g/mol.
Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³. Noble-gas notation: [Ar] 3d¹⁰ 4s² 4p³.