Group 18: Noble Gases (Inert Gases)

Group 18 of the periodic table consists of the noble gases: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). These elements are characterized by their extremely low chemical reactivity due to a full valence shell of electrons, which gives them a stable electronic configuration. Noble gases are monoatomic, colorless, odorless, and tasteless gases under standard conditions.

Electronic Configuration and Stability

Noble gases have completely filled outer electron shells, typically ns² np⁶ (except helium, which has 1s²). This configuration makes them highly stable and inert. (Learn about electronic configuration)

Physical Properties

Group - Noble Gases — Group – Noble Gases

All are colorless, odorless, and tasteless gases.
Very low boiling and melting points due to weak van der Waals forces.
Density and atomic size increase down the group.
Nonflammable and non-toxic (except radon, which is radioactive).

Chemical Properties

Extremely low reactivity due to full valence shells.
Helium is completely inert.
Krypton and xenon form compounds like KrF₂ and XePtF₆.
Radon is radioactive and forms unstable compounds.

Uses of Noble Gases

Helium: Balloons, airships, and MRI coolants.
Neon: Neon advertising signs.
Argon: Welding shielding gas, lighting.
Krypton/Xenon: Flash lamps, lasers.
Radon: Limited use in radiotherapy (radioactive hazard).

Quiz: Test Your Knowledge

Why are noble gases chemically inert?
Which noble gas has the lowest atomic mass?
Give an example of a noble gas compound.
Name two uses of argon gas.
Why is radon hazardous?

Answers

Full valence shells make them inert.
Helium is the lightest noble gas.
Example: XePtF₆, KrF₂.
Argon: Welding gas, lighting.
Radon: Radioactive, causes lung cancer.

Frequently Asked Questions (FAQs)

Q1: Why are noble gases called inert gases?
A: Because they rarely react due to stable electron configuration.

Q2: Which noble gas glows red-orange in discharge tubes?
A: Neon.

Q3: What makes radon different from other noble gases?
A: Radon is radioactive.