As
Arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. It has a standard atomic weight of 74.922, sits in period 4 and group 15, and is classified as a metalloid.
Properties
| Symbol | As |
|---|---|
| Atomic number | 33 |
| Standard atomic weight | 74.922 |
| Category | Metalloid |
| Group | 15 |
| Period | 4 |
| Electron configuration | [Ar] 3d10 4s2 4p3 |
| Outer-shell electrons | 5 |
The figure of 74.922 is a standard atomic weight.
Compounds containing arsenic
1 of the compounds in this reference contain As, listed by the fraction of their mass it makes up.
| Compound | Formula | Atoms | % by mass |
|---|---|---|---|
| arsenic trioxide | As2O3 | 2 | 75.7% |
Calculate with arsenic
- Molar mass of any formula containing it
- Electron configuration, including ions
- Effective nuclear charge by Slater's rules
- Average atomic mass from isotope abundances
Group 15
Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.