18Ar39.95
Argon
Noble gas · element 18 · group 18, period 3
Quick facts
| Symbol | Ar |
|---|---|
| Atomic number | 18 |
| Relative atomic mass | 39.95 |
| Category | Noble gas |
| Position | group 18, period 3 |
| State at 20 °C | Gas |
| Melting point | -189.3 °C |
| Boiling point | -185.8 °C |
| Density | 0.002 g/cm³ |
| Electronegativity | — |
| Electron configuration | [Ne] 3s2 3p6 |
About Argon
Argon has the symbol Ar and atomic number 18, which means every argon atom has 18 protons in its nucleus and, in a neutral atom, 18 electrons. At room temperature it is a gas.
Noble gases are in group 0. They have a full outer shell of electrons, so they are very unreactive and exist as single atoms.
It melts at -189.3 °C and boils at -185.8 °C.
Explore it
See where argon sits, and drag the temperature slider to watch it melt and boil, on the interactive periodic table. Practise with quizzes on OmniEx.