We explain what noble gases are, how they were discovered, what their uses, applications, other characteristics and examples are.
What are noble gases?
In chemistry, noble gases or inert gases are called a set of chemical elements that make up group 18 (VIIIA) of the Periodic Table of the elements.
Their main characteristic in common is their very low degree of chemical reactivity that is, its low propensity to form molecules and compounds with other elements. In fact, there is only a small set of compounds from the noble gases, unlike most of the known elements that can form a greater number of chemical compounds.
Under usual temperature and pressure conditions, the noble gases are monatomic gaseous substances (that is, made up of a single atom). Many of them are present in varying proportions in the air that makes up the atmosphere.
Despite their low chemical reactivity, or sometimes as a consequence of it, these elements have very diverse applications in industry, and are usually mass produced.
Discovery of noble gases
Most noble gases were discovered during the 19th century, as a result of studies on the Sun by Pierre Janssen (French, 1824-1907) and Joseph Norman Lockyer (British, 1836-1920). These astronomers discovered helium, named after the Greek word (Helios) for the star.
The surprise at the characteristic properties of this new element opened the doors to the search for other similar ones. This is how krypton, neon and argon were discovered, from the chemical study of air.
Towards the end of the 19th century, the British researchers Lord Rayleigh (1842-1919) and William Ramsay (1852-1916) postulated the joint existence of noble gases, for which they obtained the Nobel Prize in Physics and Chemistry. Newly In the 20th century, large-scale industrial production of these gases began as more of its properties and uses were discovered.
Characteristics of noble gases
In general, noble gases are characterized by:
- Present little or no chemical reactivity that is, they do not react easily. This is because its last electronic shell or energy level is always complete.
- Be devoid of color, smell and flavor.
- Have very close and very low melting and boiling points with just 10 ºC difference, so they are almost always in a gaseous state, although they can be transformed into a liquid only in very precise temperature ranges.
- Behave like ideal gases under normal conditions of pressure and temperature (1atm and 0 ºC.) that is, it can be considered that its particles do not interact and comply with the equation of state of ideal gases:
Where:
Q. It represents the pressure of the gas and is expressed in atmospheres (atm) or equivalent units.
v. It represents the volume of the gas and is expressed in liters (L) or equivalent units.
n. It represents the amount of substance in the gas and is expressed in moles (mol).
R. It is the ideal gas constant and has a value of 8.314 joule/mol Kelvin (J/mol K).
T. It represents the temperature of the gas and is expressed in Kelvin (K) or equivalent units. - In the case of helium, has very particular properties: it has lower melting and boiling points than any known substance, it is the only element that presents superfluidity (a state of fluid that does not present viscosity, that is, it flows without friction), and it cannot transform into a solid under standard pressure conditions .
Why are they called noble gases?
Initially, these elements were called “inert gases” or “rare gases.” since it was thought at the time that they were totally chemically inert elements and, therefore, very rare in the universe. Both features turned out to be false.
Nowadays “noble gases” are preferred, translation of “Edelgas“, German term with which the chemist Hugo Erdmann (1862-1910) baptized them in 1898. Erdmann took this name from “noble metals” such as gold, whose reactivity is very moderate. So, just as gold tended to stay pure and retain its nobility, so did these gases.
Uses and applications of noble gases
These elements have numerous uses for humans, such as:
- Insulators Due to their low reactivity it is possible to use them to contain very reactive or dangerous substances.
- Cryogenic refrigerants. Through processes that extract heat and reduce pressure, gases are transformed into liquids, and these liquids are ideal for keeping delicate machinery such as superconducting magnets or nuclear magnetic resonance equipment running. Helium is widely used for this purpose.
- Breathable component. Helium mixed with other gases is used in the tanks of astronauts and divers, as it reduces the narcotic effect of the so-called “deep sickness,” which is caused by a high concentration of gases in the blood and tissues. Because helium has poor solubility, it is less likely to pass through cell membranes.
- Filling inflatable balloons or dirigibles. Helium can be used to inflate balloons as it is lighter than air and very safe, a perfect replacement for hydrogen, which is highly flammable.
- Lightning. Neon, xenon, argon and krypton can be used, filling incandescent light bulbs with them to produce specific colors of light, in what we commonly call “neon lights”.
- To make lasers. They are usually used in surgeries or industrial procedures.
Examples of noble gases
There are only seven noble gases:
- Helium (He) It is the second most abundant element in the known universe. One of the ways to obtain it is as a product of hydrogen fusion reactions in the hearts of stars. It has the peculiarity of altering the human voice when inhaled and of being much lighter than air.
- Neon (Ne) Another abundant element in the known universe. It is used to make fluorescent lamps since it gives them a red color. It is particularly used in the manufacture of televisions. It is also widely used in the production of the He-Ne laser.
- Argon (Ar) One of the common gases in the air we breathe, it is widely used as an industrial insulator and in obtaining lasers.
- Krypton (Kr) Although it is a noble gas, it can react with fluorine and a few other highly electronegative substances, and it has six stable isotopes and seventeen radioactive isotopes.
- Xenon (Xe) It is a very heavy gas, present only in traces in the Earth's atmosphere. It was the first of the noble gases to be artificially synthesized.
- Radon (Rn) Result of the radioactive decay of elements such as radium or actinium (for that reason it was previously called actinon), is a noble but radioactive gas, whose most stable isotope can last a maximum of 3.8 days, before decaying to polonium-218.
- Oganeson (Og) Also called eka-emanationununoctium (Uuo) or element 118, this mysterious noble gas is highly radioactive and of synthetic origin, that is, it does not exist in nature. It was “discovered” in 2002.
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References
- “Noble gases” https://es.wikipedia.org/
- “Periodic table #9. Group 18. Noble gases” (video) in Cienciabit. https://www.youtube.com/
- “Noble gas” http://enciclopedia.us.es/
- “What is noble about noble gases?” https://www.fisicanet.com.ar/
- “Noble gas” https://www.britannica.com/
