Noble Gases: Elements, Properties and Sample Questions

Noble gases are important elements of the periodic table. They belong to the 18th group and have similar properties. Noble gases are odorless, colorless, and have low reactivity. In this article, we will learn more about various noble gases, their properties, and related sample questions.

Keyterms: Noble gas, Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), Aerogens

Read Also:- p Block Elements

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What are Noble Gases?

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The elements belonging to Group 18 of the periodic table are noble gases. The noble gases are also known as the 'Inert Gases' or 'Aerogens'. The noble gases or the elements belonging to group 18 of the periodic table are -

• Helium (He)
• Neon (Ne)
• Argon (Ar)
• Krypton (Kr)
• Xenon (Xe)
• Radon (Rn)

German chemist Hugo Erdmann termed these gases as 'noble gas' in 1898. The noble gases exist in the gaseous phase in normal temperature and pressure. The general configuration of the noble gases is ns²np⁶. Because of the stable electronic configuration, the noble gases have very low reactivity. And because of low reactivity, they don't form molecules easily and are generally found as mono-atomic gases.

Let us explore the properties of various noble gases.

Also check: Metals and Non-metal

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Helium (He)

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• The atomic number of Helium is 2. It is denoted by the symbol He.
• Helium is the first and the lightest of all noble gases.
• The atomic mass of Helium is 4.0002602 u.
• The electronic configuration of Helium is 1s².
• There are 2 electrons in the valence shell of Helium.
• Under the normal conditions for temperature and pressure, Helium exists as a colorless, odorless, tasteless, mono-atomic gas.
• In small concentrations, Helium is non-toxic.
• Under the normal conditions for temperature and pressure, the density of Helium is 1.7186 grams per liter.
• The melting point of Helium is approximately -272° C.
• The boiling point of Helium is -268.9° C.

Helium Atom

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Neon (Ne)

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• The atomic number of Neon is 10. It is denoted by the symbol Ne.
• Neon is the second lightest of all the noble gases.
• The atomic mass of Neon is 20.1797 u.
• The electronic configuration of Neon is 2s²2p⁶.
• There are 8 electrons in the valence shell of Neon.
• Under the normal conditions for temperature and pressure Neon exists as a colorless, odorless, mono-atomic gas.
• Under the normal conditions for temperature and pressure, the density of Neon is approximately 0.9 grams per liter.
• The melting point of Neon is approximately -248.59°C.
• The boiling point of Neon is -246°C.

Neon Atom

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Argon (Ar)

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• The atomic number of Argon is 18. It is denoted by the symbol Ar.
• Argon is the 3rd most abundant gas in the earth's atmosphere.
• The atomic mass of Argon is 39.948 u.
• The electronic configuration of Argon is 3s² 3p⁶.
• There are 8 electrons in the valence shell of Argon.
• Under the normal conditions for temperature and pressure, Argon exists as a colorless gas.
• When placed in an electric field Argon exhibits a violet or lilac-colored glow.
• Under the normal conditions for temperature and pressure, the density of Argon is approximately 1.784 grams per liter.
• The melting point of Argon is approximately -189.4° C.
• The boiling point of Argon is -185.8° C.

Argon Atom

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Krypton (Kr)

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• The atomic number of Krypton is 36. It is denoted by the symbol Kr.
• The atomic mass of Krypton is 83.798 u.
• The electronic configuration of Krypton is 3d¹⁰4s²4p⁶.
• Under the normal conditions for temperature and pressure, Krypton exists as a colorless, odorless, tasteless mono-atomic gas.
• Under the normal conditions for temperature and pressure, the density of Krypton is approximately 3.75 grams per liter.
• The melting point of Krypton is approximately -157.4° C.
• The boiling point of Krypton is -153.4° C.

Krypton Atom

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Xenon (Xe)

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• The atomic number of Xenon is 54. It is denoted by the symbol Xe.
• The atomic mass of Xenon is 131.293 u.
• The electronic configuration of Xenon is 4d¹⁰5s²5p⁶.
• Under the normal conditions for temperature and pressure xenon exists as a colorless, odorless, mono-atomic gas.
• Under the normal conditions for temperature and pressure, the density of Xenon is approximately 5.89 grams per liter.
• The melting point of Xenon is approximately -111.75° C.
• The boiling point of Xenon is -108.1° C.

Xenon Atom

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Radon (Rn)

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• The atomic number of Radon is 86. It is denoted by the symbol Rn.
• The atomic mass of Radon is 222.01758 u.
• The electronic configuration of Radon is 4f¹⁴5d¹⁰6s²6p⁶.
• Under the normal conditions for temperature and pressure, Radon exists as a colorless, odorless, tasteless, mono-atomic gas.
• Radon is a radioactive gas. It is generated by the radioactive decay of Radium.
• Under the normal conditions for temperature and pressure, the density of Radon is approximately 9.73 grams per liter.
• The melting point of Neon is approximately -71° C.
• The boiling point of the Radon is -61.7°C.

Radon Atom

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Things to Remember

• The elements belonging to Group 18 of the periodic table are noble gases.
• The noble gases or the elements belonging to group 18 of the periodic table are – Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn)
• Helium is the first and the lightest of all noble gases. The atomic number of Helium is 2. It is denoted by the symbol He.
• Neon is the second lightest of all the noble gases. The atomic number of Neon is 10. It is denoted by the symbol Ne.
• Argon is the 3rd most abundant gas in the earth's atmosphere. The atomic number of Argon is 18. It is denoted by the symbol Ar.
• Krypton has an atomic number of 36. It is denoted by the symbol Kr.
• Xenon has the atomic number of 54. It is denoted by the symbol Xe.
• Radon has the atomic number of 86. It is denoted by the symbol Rn.

Also Read:

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Previous Year Questions

1. Elements of which of the following groups will form anions most readily?..[NEET 1992]
2. Which of the following is a nitric acid anhydride?...[NEET 1988]
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6. Which among the following is paramagnetic?..[NEET 1994]
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9. Pure nitrogen is prepared in the laboratory by heating a mixture of...[NEET 1991]
10. PH4​I+NaOH forms….[NEET 1991]
11. PCl3​ reacts with water to form..[NEET 1991]
12. P2​O5​ is heated with water to give...[NEET 1991]
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