How are rare gases discovered?

In the 1990s, people thought that there were only two components in the air: oxygen and nitrogen. British scientist Rayleigh decided to measure the density of nitrogen. He made nitrogen in two different ways. One is to combine oxygen in the air with copper, thinking that the rest is nitrogen, and the measured density is1.2572 g/L. The second method is to react oxygen with ammonia to generate water and nitrogen, and the measured density is1.2508 g/L. The difference between the two methods is 0.0064g g.

Rayleigh repeated the measurement many times, and the result was the same. He was puzzled, so he asked another scientist Ramsey to help him gradually remove water vapor, carbon dioxide, oxygen and nitrogen from the air through a series of chemical reactions. Finally, he found a new gas element, whose density is about 20 times that of hydrogen, and its content in the air is very low. This element is very special in nature and hardly reacts with any substance. Scientists named it argon, which means it is lazy.

A few years later, Ramsey discovered another new element in pitchblende. Through spectral analysis, it is confirmed that this is the first time that astronomers discovered helium on the sun more than 20 years ago.

After that, Ramsey made the air into a liquid state through a refrigerator, and then separated various gases by condensation and volatilization according to the different boiling points of various gases, and successively discovered three new elements: krypton, neon and xenon. Their proportions in air are: argon 0.94%, neon 0.00 18%, helium 0.0005%, krypton 0.00 1 1% and xenon 0.000009%. They are called rare gases because their content is very small. Under normal circumstances, the chemical properties of rare gases are very inactive and it is not easy to react with other substances, so they are also called inert gases. On the periodic table of elements, helium, neon, argon, krypton and xenon are arranged as a group, that is, zero group elements.

Ramsey won the Nobel Prize in chemistry from 65438 to 0904, and Rayleigh won the Nobel Prize in physics in the same year.