Why were noble gases last to be discovered?

Answer 1

1. They are rare, both in occurence and concentration
2. They do not react (readily) so exhibit no influential existence.
3. Being much less reactive, they do not appear in any common materials
4. They are colourless, odorless, have no readily identifiable properties.

Because of this, they required isolation from scattered deposits, and required the existence of spectrometry before they could be readily detected. In the case of xenon, commercial production requires an energy-intensive, relatively expensive process (liquification of air).

Answer 2

They are very unreactive and thus are present only in the atomsphere. Therefore they could only be identified once they could separate the components of air. Also they are present in very small concentrations. The exception is argon making up 0.93% of the earths atmosphere. Their small concentrations made it much harder to identify them.

Answer 3

Along the extreme right hand column of the Periodic Table of elements is a group known as the noble gases: helium, neon, argon, krypton, xenon, and radon. Also known as the rare gases, they once were called inert gases, because scientists believed them incapable of reacting with other elements. Rare though they are, these gases are a part of everyday life, as evidenced by the helium in balloons.

'Noble gases' is one of the most common names for the elements in the rightmost group of the periodic table of the elements. They are also sometimes called 'inert gases'. For a number of complicated reasons, these elements have one important chemical property: they are extremely nonreactive. One consequence of this was that the noble gases were isolated and characterised only relatively late.

The first person to actually isolate and note the presence of these noble gases was Henry Cavendish (1731-1810: chemistry bigwig and discoverer of hydrogen) in 1785. He removed all the nitrogen and oxygen chemically from a receptacle containing air. The nitrogen was oxidised to NO2 by electric discharges and absorbed by a sodium hydroxide solution. Remaining oxygen was removed from the mixture by a special adsorber. 1/120 of the gas volume remained unreacted in the receptacle. As we know today, this must have been mainly argon (99.8%) and traces (0.2%) of other noble gases. The second person to isolate a noble gas, but without characterising it, was mineralogist William Francis Hillebrand (1853-1925) who noted the formation of a gas while dissolving uranium containing minerals in acid. We know today this must have been helium.

Answer 4

hey were last to be discovered because they were not visible!

Answer 5

Because they don't react with anything else; when you're looking for reactions, noble gasses are invisible.