ARGON
NOBLE GAS
| Atomic number: | 18 |
| Group numbers: | 18 |
| Period: | 3 |
| Electronic configuration: | [Ne] 3s2 3p6 |
| Formal oxidation number: | 0 |
| Electronegativities: | - |
| Atomic radius / pm: | 188 |
| Relative atomic mass: | 39.948(1) |
Argon was discovered by Lord Raleigh and Sir William Ramsay (GB) in 1894. The origin of the name comes from the Greek word argos meaning inactive. It is a colourless and odourless noble gas, chemically inert. Argon is the third most abundant element in the earth's atmosphere and makes up about 1%. Argon is continuously released into the air by decay of radioactive potassium-40. Pure form is obtained from fractional distillation of liquid air. It is used in lighting products, and is often used in filling incandescent light bulbs. Some is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are grown in argon atmospheres. The price of 99.999 % pure argon gas costs 169.90 €/dm3 in small quantities (1 dm3) and about 1.84 €/dm3 in large quantities (300 dm3).
| Density / g dm-3: | 1656 | (40 K) |
| 1.784 | (273 K) | |
| Molar volume / cm3mol-1: | 24.12 | (40 K) |
| 22392.38 | (273 K) | |
| Electrical resistivity / µΩcm: | - | (20 °C) |
| Thermal conductivity / W m-1K-1: | 0.0179 |
| Melting point / °C: | -189.34 |
| Boiling point / °C: | -185.89 |
| Heat of fusion / kJ mol-1: | 1.21 |
| Heat of vaporization / kJ mol-1: | 6.53 |
| Heat of atomization / kJ mol-1: | 0 |
| First ionization energy / kJ mol-1: | 1520.58 |
| Second ionization energy / kJ mol-1: | 2665.88 |
| Third ionization energy / kJ mol-1: | 3930.84 |
| in the atmosphere / ppm: | 9300 |
| in the Earth's crust / ppm: | 1.2 |
| in the oceans / ppm: | 0.6 |
| Crystal structure: | face-centered cubic |
| Unit-cell dimensions / pm: | a=531.088 |
| Space group: | Fm3m |
| Isotope | Relative atomic mass | Mass percent (%) |
|---|---|---|
| 36Ar | 35.9675463(3) | 0.337(3) |
| 37Ar | 36.9667759(3) | * |
| 38Ar | 37.9627322(5) | 0.063(1) |
| 39Ar | 38.964313(5) | * |
| 40Ar | 39.962383123(3) | 99.600(3) |
| Balanced half-reaction | Eo / V | |
|---|---|---|
| 17 Chlorine | ← | 18 Argon | → | 19 Potassium |
Citing this page:
Generalic, Eni. "Argon." EniG. Periodic Table of the Elements. KTF-Split, 13 Feb. 2025. Web. {Date of access}. <https://www.periodni.com/ar.html>.
