18Ar39.948
Argon (Ar)
Element 18 Ā· Noble gas
Argon (Ar) is a chemical element with atomic number 18. It is classified as a noble gas in period 3, group 18 of the periodic table (the p-block). Its standard atomic weight is 39.948 u and its ground-state electron configuration is [Ne] 3sĀ² 3pā¶.
Argon facts
| Atomic number (Z) | 18 |
|---|---|
| Symbol | Ar |
| Standard atomic weight | 39.948 u |
| Category | Noble gas |
| Group | 18 |
| Period | 3 |
| Block | p-block |
| Electron configuration | [Ne] 3sĀ² 3pā¶ |
| Electronegativity (Pauling) | ā |
| State at 20 Ā°C | Gas |
| Protons / electrons | 18 / 18 |
| Neutrons (most common isotope, approx.) | 22 |
| Molar mass | 39.948 g/mol |