- What are noble gases?
- Discovery of noble gases
- Noble gas characteristics
- Why are they called noble gases?
- Uses and applications of noble gases
- Examples of noble gases
We explain what noble gases are, how they were discovered, what are their uses, applications, other characteristics and examples.
Noble gases such as helium are very safe due to their low reactivity.What are noble gases?
In chemistry, is called noble gases or inert gases to 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, their low propensity to form molecules Y compounds with other elements. In fact, there is only a small set of compounds from noble gases, unlike most of the known elements that can form a greater amount of chemical compounds.
In conditions of temperature Y Pressure common, noble gases are substances monatomic gaseous (that is, made up of a single atom). Many of them are present in varying proportions in the air that integrates the atmosphere.
Despite their low chemical reactivity, or sometimes as a consequence of it, these elements have very diverse applications in the industry, and are usually mass-produced.
Discovery of noble gases
Most of the noble gases were discovered during the 19th century, as a consequence of studies on the Sun by Pierre Janssen (French, 1824-1907) and Joseph Norman Lockyer (British, 1836-1920). These astronomers discovered helium, named for the Greek word (Helios) for him star.
The surprise at the properties The characteristics 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, with which they obtained the Nobel Prize for Physical and Chemistry. It was only in the 20th century that industrial production of these gases began on a large scale, as more of their properties and uses were discovered.
Noble gas characteristics
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 layer or energy level is always full.
- Be devoid of color, smell and taste.
- Introduce melting points Y boiling very close and very low, with barely 10 ºC of difference, so they are almost always in gaseous state, although they can be transformed to liquid only in very precise temperature ranges.
- Behave as ideal gases under normal conditions of pressure and temperature (1atm and 0 ºC.), That is, it can be considered that their particles They do not interact and comply with the equation of state for ideal gases:
Where:
-
- P. It represents the pressure of the gas and is expressed in atmospheres (atm) or equivalent units.
- V. Represents the volume of gas and is expressed in liters (L) or equivalent units.
- n. 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, it 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 the fluid that does not present viscosity, that is, it flows without friction), and cannot be transformed into solid under standard pressure conditions.
Why are they called noble gases?
Initially, these elements were baptized "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 world. universe. Both features turned out to be false.
Nowadays "noble gases" is preferred, translation of "Edelgas", The German term with which the chemist Hugo Erdmann (1862-1910) baptized them in 1898. Erdmann took this name from the" 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 the human being, such as:
- Insulators Due to their low reactivity it is possible to use them to contain highly reactive or dangerous substances.
- Cryogenic refrigerants. Through processes that extract heat and decrease the Pressure, gases are transformed into liquids, and these liquids are ideal for keeping delicate machinery such as magnets superconductors or nuclear magnetic resonance equipment. Helium is widely used for this purpose.
- Breathable component. Helium mixed with other gases is used in the tanks of astronauts and divers, since it reduces the narcotic effect of the so-called "depth sickness", which is caused by a high concentration of gases in the blood and tissues. Since helium has poor solubility, it is less likely to pass through cell membranes.
- Filled with inflatable balloons or airships. 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.
- Illumination. Neon, xenon, argon and krypton can be used and filled with incandescent bulbs to produce specific colors of light, in what we ordinarily call "neon lights."
- To make lasers. They are often used in surgeries or industrial procedures.
Examples of noble gases
The noble gases are only seven:
- 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 heart of the 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 as 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 electronegativity 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 disintegrating to polonium-218.
- Oganeson (Og). Also called eka-emanation, ununoctium (Uuo) or element 118, this mysterious noble gas is highly radioactive and of synthetic origin, that is, it does not exist in the nature. It was "discovered" in 2002.