Discovery of noble gases :
Discovery of Noble gases took place in a period of one century (1795 – 1898). Ramsay and Rayleigh were awarded the Nobel prize for their studies on Noble gases. The noble gases are colourless, odourless, tasteless, and nonflammable gases.
Noble gases list :
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Oganesson (Og)
Properties of Noble gases :
|Boiling point (K)||4.4||27.3||87.4||121.5||166.6||211.5|
|Melting point (K)||0.95
(at 25 bar)
|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 radius (calculated) (pm)||31||38||71||88||108||120|
|Ionization energy (kJ/mol)||2372||2080||1520||1351||1170||1037|
Discovery of Helium :
Janssen and Lockyer discovered Helium (He) in their spectroscopic studies of the solar spectrum. As He present in the atmosphere of the sun, it is named Helium (Helios = Sun). Later, Ramsay separated it from earth’s atmosphere.
Discovery of Argon :
In 1891, Rayleigh observed that the density of gas isolated from the atmosphere is higher than the gas obtained from chemical compounds. He also predicted that an inert gas with the atomic weight of 40 is associated with gas obtained from atmospheric Nitrogen. This gas was named as Argon (= lazy) being it is chemically inert. But, later it was found that this Argon was a mixture of several other inert gases.
Discovery of Neon, Krypton and Xenon :
Ramsay and Travers isolated inert gases fraction from the atmospheric Nitrogen and subjected it to fractional distillation at different reduced pressures. Then, they separated a new element with an atomic weight of 20.2 and named it as Neon (Neon = New).
Ramsay repeated fractional distillation of liquid air and discovered Krypton (= Hidden) and Xenon (= Stranger).
In 1900, Radon gas was discovered from the radioactive disintegration of Radium. Radon is a radioactive element and does not present in the air.