What are Noble Gases?

Dhristi JEE 2022-24

Introduction of Noble Gases

Any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table are considered noble gases. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). Noble gases are colourless, odourless, and tasteless nonflammable gases. Because it was assumed for decades after their discovery that they couldn't link to other atoms and that their atoms couldn't combine with those of other elements to produce chemical compounds, they were allocated to Group 0 in the periodic table. Group 18 is a better classification based on their electrical properties and the discovery that some of them do form compounds.

Noble Gases and Their Applications

Inert atmospheres, which are commonly used for arc welding, specimen protection, and chemical reaction prevention, are created using noble gases. Neon lights and krypton headlights, as well as lasers, contain the elements. Superconducting magnets are cooled with helium, which is also used in balloons and deep-sea diving air tanks.

The Noble Gases' Sources

Air contains neon, argon, krypton and xenon, which are obtained by liquefaction and  fractional distillation. Cryogenic separation of natural gas is the most important source of helium. Radioactive decay of heavy elements such as radium, thorium, and uranium produces radon, a radioactive noble gas. Element 118 is a radioactive element produced by the acceleration of particles and their impact on the target. Noble gas alien sources  may be discovered in the future. Large planets have more helium deposits than Earth.

Noble Gas Properties: Key Takeaways

  • On the periodic table, noble gases belong to group 18, which is the right-hand column of elements.

  • Helium, neon, argon, krypton, xenon, radon, and oganesson are the seven noble gases.

  • The least reactive chemical elements are noble gases. Because the atoms have a full valence electron shell, they are practically inert and have minimal tendency to absorb or contribute electrons to form chemical bonds.

Excimer lasers, which are based on short-lived electrically excited molecules known as excimers, also use noble gases. Noble gas dimers like Ar2, Kr2, or Xe2 are employed in lasers, but more typically, the noble gas is coupled with a halogen in excimers like ArF, KrF, XeF, or XeCl. These lasers produce ultraviolet light, which enables high-precision imaging due to its short wavelength (193 nm for ArF and 248 nm for KrF). Excimer lasers have a wide range of industrial, medical, and scientific uses. They are used in integrated circuit production for microlithography and microfabrication, as well as laser surgery, such as laser angioplasty and eye surgery.

The noble gases are group 18 elements of the periodic table. Atoms of these elements have completely filled valence electron shells, making them relatively inert, colourless, odourless, monatomic gases at room temperature and pressure. 


Under the normal conditions of temperature and pressure, all the noble gases exist in the gaseous phase. The term “noble gas” is derived from a translation of the German word Edelgas, which means “noble gas”. 

German chemist Hugo Erdmann termed this phrase in 1898. Like a nobleman considers it undignified to associate with common people, noble gases tend not to react with other elements. Other names for noble gases are rare gases, inert gases, and aerogenes. 


The Names of the Noble Gases are:

  • Helium (He)

  • Neon (Ne)

  • Argon (Ar)

  • Krypton (Kr)

  • Xenon (Xe)

  • Radon (Rn)

Noble Gas Properties

They are known to have extremely low chemical reactivity. This is because all the inert gases have stable electron configurations and they do not form molecules easily and are mostly found as monatomic gases. The general noble gas configuration is ns2 np6. In this topic we have discussed the definition of noble gases definition, Now let’s discuss noble gases properties and the atomic number of noble gases.


Helium (He):

Helium is the first chemical element of group 18 and is denoted by the symbol He. It is the first lightest noble gas and is known to possess the lowest boiling point. It is the second lightest element which is colourless, odourless, and tasteless. The atomic number of helium is 2. It is non-toxic in small concentrations, The electronic configuration of helium is 1s2. So, It has a total of 2 electrons in its valence shell. Helium cannot be solidified by sufficient cooling at normal atmospheric pressure, so it is necessary to apply pressure of 25 atmospheres at a temperature of −272 °C to convert it into a solid form.


This gas constitutes about 23 percent of the mass of the universe and is the second in abundance after hydrogen in the cosmos. Helium is mainly concentrated in stars, where it is synthesized from hydrogen by the nuclear fusion reaction. This gas is used as an inert-gas atmosphere for welding metals such as aluminium and is also used in rocket propulsion.

  • Atomic Number: 2

  • Mass Number: 4

  • Melting point: -272 °C

  • Boiling Point: -268.9 °C

  • Density: 0.178 X 10 -3 g/cm3 at 20 °C


Neon (Ne):

Neon is a second chemical element of group 18 and is denoted by the symbol Ne. The atomic number of neon is 10. Neon exists as a colourless monoatomic gas. This gas does not possess any colour, odour, taste and is lighter than air. The electronic configuration  of Neon is HeHe 2s22p6. It is used commonly in fluorescent lamps and electric signs. This gas occurs in minute quantities in Earth’s atmosphere and is trapped within the rocks of Earth’s crust. This element is more abundant in the cosmos as compared to Earth’s surface. 

  • Atomic Number: 10

  • Mass Number: 20

  • Melting point: -248.4 °C

  • Boiling Point: -246 °C

  • Density: 0.9 g/L

Argon (Ar):

Argon is the third chemical element of group 18 in the periodic table with an atomic number of 18. The element is denoted by the symbol Ar. It is a colourless, odourless, and tasteless gas. The electronic configuration of argon is NeNe3s23p6. This element has a total of 8 electrons in its valence shell and hence it is non-reactive.

  • Atomic Number: 18

  • Mass Number: 39.948

  • Melting point: -189.4 °C

  • Boiling Point: -185.8 °C

  • Density: 1.784 g/L


Krypton (Kr):

Krypton is the fourth chemical element of group 18 with an atomic number equal to 36. This element is denoted by the symbol Kr. It is about three times heavier compared to air. Krypton is a colourless, odourless, tasteless, and monatomic gas. The electron configuration of krypton is written as ArAr3d104s24p6.  

  • Atomic Number: 36

  • Mass Number: 83.798

  • Melting point: -157.4 °C

  • Boiling Point: -153.4 °C

  • Density: 1.784 g/L



Xenon is the fifth noble gas with an atomic number of 54. The symbol ‘Xe’ is used to denote xenon.

It is 4.5 times heavier than air, It is a colourless, odourless, and tasteless gas. The term xenon was derived from the Greek word Xenos, meaning “strange” or “foreign.”

  • Atomic Number: 54

  • Mass Number: 131.293

  • Melting point: -157.4 °C

  • Boiling Point: -108.1 °C

  • Density: 5.761 kg/m3



Radon is a sixth noble gas with an atomic number equal to 86. It is a heavy radioactive gas generated by the radioactive decay of radium. This is a colourless gas that is 7.5 times heavier compared to air and 100 times heavier than hydrogen.

  • Atomic Number: 86

  • Mass Number: 222.01

  • Melting point: -71 °C

  • Boiling Point: -61.7 °C

  • Density: 9.73 g/litre

Here, we have discussed all the noble gas elements. 

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FAQs (Frequently Asked Questions)

1. How many Noble Gases are there in the Periodic Table?

There are six noble gases in the periodic table: helium, neon, argon, krypton, xenon, and radon. Noble gases are a group of chemical elements with similar properties. They are all odorless, colorless monatomic gases and have little chemical reactivity under normal conditions. Helium, neon, argon, krypton, xenon, and radon are noble gases and are classified by density.They're termed noble gases because they're so beautiful that they don't react with anything in general. As a result, they are also referred to as inert gases.

2. Write some properties of noble gases.

Some properties of noble gases are shown below. 

They are non-reactive and are used to create an inert atmosphere. They have a complete external electron or valence shell.  They have high ionization energy. Electronegativity is very low. The boiling point is low. (All are monatomic gases at room temperature). Under normal conditions, there is no color, odor or taste. Not flammable. At low pressures, it conducts electricity and fluoresces. 

3.What is the difference between octet and double? 

The main difference between the octet and the double is that the octet is an atom or  ion with up to 8 electrons in the outermost shell. A doublet, on the other hand, is an atom with up to two electrons in its outermost shell.

According to the Duplet rule, an element is stable if its valence shell has two electrons, and to achieve this condition, elements lose, gain, or share electrons while forming chemical bonds. The duet rule is another name for this regulation. Hydrogen, Helium, and Lithium are the only elements known to follow this criterion.

4. What are the properties of noble gases?

Noble gases have a low chemical reactivity and are odourless, colourless, non-flammable, and monotone. Noble gases contain entire valence electron shells, making them exceedingly stable and unable to form chemical bonds due to their low inclination to receive or lose electrons. They are thus- Relatively reactive, (oxidation number = 0) Complete outer electron or valence shell, Ionization energies that are very high, Electronegativities are quite low, and Boiling points are low (all monatomic gases at room temperature).