Arsenic (As)
Element 33 · Metalloid
Arsenic (As) is a chemical element with atomic number 33. It is classified as a metalloid in period 4, group 15 of the periodic table (the p-block). Its standard atomic weight is 74.922 u and its ground-state electron configuration is [Ar] 3d¹⁰ 4s² 4p³.
Arsenic facts
| Atomic number (Z) | 33 |
|---|---|
| Symbol | As |
| Standard atomic weight | 74.922 u |
| Category | Metalloid |
| Group | 15 |
| Period | 4 |
| Block | p-block |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p³ |
| Electronegativity (Pauling) | 2.18 |
| State at 20 °C | Solid |
| Protons / electrons | 33 / 33 |
| Neutrons (most common isotope, approx.) | 42 |
| Molar mass | 74.922 g/mol |