Noble gas was discovered by a french astronomer Pierre’s Janssen in the year 1868. But before then noble gas was mistakenly isolated by henry cavendish in the year 1785 when he was investigating the compositions of air. Henry cavendish experiment that led to the discovery of noble gas were;
He mixed excess of oxygen with air and subject the mixture to pass through electric spark on the mixture the oxide of nitrogen formed was removed via the dissolution of the mixture in alkali solution and excess of oxygen were also removed when the solution was reacted with potassium sulphate.
After the removal of the two oxides nitrogen and oxygen, cavendish found a read residues of gas left and this residues is neither nitrogen nor oxygen and its formation did not exceed 1/120th component of the original volume of air. What cavendish actually isolated were noble gas but at that time it was not the appropriate time two discovered noble gas because he could not characterized them. But the most interesting story about cavendish isolation is that the figure of the residual gas is remarkably near to the proportions of the atmospheric noble gas as we now known today.
After cavendish investigation it take almost a century before final discovery of noble gas the discovery come as a result of advanced spectroscopy, periodic classification, and the study of radioactive element.
Discovery of noble gas
the first noble gas to be discovered is the helium. Helium was discovered in a special way on the extraterrestrial before it was found on earth.
Pirre Janssen was a French astronomer who travel to India to study the eclipse of the sun in the year 1868. When Janssen uses his spectroscopy to view the eclipse of the sun he observed a new yellow line near the sodium D line in the sun chromophore spectrum. this new yellow line viewed by Janssen, project to englishman chemist E. Frankland astronomer and Sir J. Norman Lockyer to assume that there is existence of new element which is not yet discovered which is the element helium. Helium which derives its name from Greek word Helios meaning the sun. But Sir William Ramsay establish the terrestrial existence of helium in the year 1895.