[Chemistry Class Notes] on What are Noble Gases? Pdf for Exam

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.

 

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. 

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.

 

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.  

 

Xenon(Xe):

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.”

 

Radon(Rn):

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.