The rare gases, also known as the noble gases or the inert gases, are a group of six gaseous elements found in small amounts in the atmosphere: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Collectively they make up about one percent of Earth’s atmosphere.
They were discovered by scientists near the end of the nineteenth century, and because they were so unreactive were initially called the inert gases.
The properties of each rare gas dictate its specific commercial applications. Because they are the most abundant, and therefore the least expensive to produce, helium and argon find the most commercial applications. Helium’s low density and inertness make it ideal for use in lighter-than-air craft, such as balloons and blimps. Because of its extremely low temperature Liquid helium is used in MRIs and NMR
Neon is well known for its use in neon signs. Glass tubes of any shape can be filled with neon and when an electrical charge is passed through the tube, an orange red glow is emitted. By contrast, ordinary incandescent light bulbs are filled with argon. Because argon is so inert, it does not react with the hot metal filament and prolongs the bulb’s life. Argon is also used to provide an inert atmosphere in welding and high-temperature metallurgical processes. By surrounding hot metals with inert argon, the metals are protected from potential oxidation by oxygen in the air. Krypton and xenon also find commercial lighting applications. Krypton can be used in incandescent light bulbs
Fine Gas along with its partners offers rare gases and rare gas mixtures in a variety of purities and concentrations.
Properties of Rare Gases
Property |
Helium |
Neon |
Argon |
Krypton |
Xenon |
Radon |
Density (g/dm3) | 0.1786 | 0.9002 | 1.7818 | 3.708 | 5.851 | 9.97 |
Boiling point (K) | 4.4 | 27.3 | 87.4 | 121.5 | 166.6 | 211.5 |
Melting point (K) | 0.95 | 24.7 | 83.6 | 115.8 | 161.7 | 202.2 |
Enthalpy of vaporization (kJ/mol) | 0.08 | 1.74 | 6.52 | 9.05 | 12.65 | 18.1 |
Solubility in water at 20 °C (cm3/kg) | 8.61 | 10.5 | 33.6 | 59.4 | 108.1 | 230 |
Atomic number | 2 | 10 | 18 | 36 | 54 | 86 |
Atomic radius (calculated) (pm) | 31 | 38 | 71 | 88 | 108 | 120 |
Ionization energy (kJ/mol) | 2372 | 2080 | 1520 | 1351 | 1170 | 1037 |
Electronegativity | 4.16 | 4.79 | 3.24 | 2.97 | 2.58 | 2.60 |