Group 0 — Noble Gases | Chemistry

📖 In-Depth Theory

Properties of the Noble Gases

GROUP 0 (also called Group 18) contains the NOBLE GASES:

Helium (He) — atomic number 2.

Neon (Ne) — atomic number 10.

Argon (Ar) — atomic number 18.

Krypton (Kr) — atomic number 36.

Xenon (Xe) — atomic number 54.

Radon (Rn) — atomic number 86.

All noble gases are:

COLOURLESS gases at room temperature.

MONATOMIC — they exist as single atoms, not molecules (unlike O₂, N₂, Cl₂).

EXTREMELY UNREACTIVE — they do not form compounds under normal conditions.

DENSER than air as you go down the group.

Have very LOW BOILING POINTS — they remain gases until very cold.

Why Noble Gases Are Unreactive

Noble gases are unreactive because they have FULL OUTER ELECTRON SHELLS:

Helium: 2 electrons (full 1st shell).

Neon: 2.8 (full 1st and 2nd shells).

Argon: 2.8.8 (full 1st, 2nd and 3rd shells).

A full outer shell is the most STABLE electron configuration — the atom has no tendency to gain, lose or share electrons.

This is why other elements react — they are trying to ACHIEVE the stable full outer shell configuration of a noble gas:

Group 1 metals lose 1 electron → achieve noble gas configuration.

Group 7 non-metals gain 1 electron → achieve noble gas configuration.

Non-metals share electrons (covalent bonds) to achieve full outer shells.

Trends Down Group 0

Going DOWN Group 0 (from He to Rn):

ATOMIC RADIUS increases — more electron shells are added.

BOILING POINT INCREASES:

He: −269°C, Ne: −246°C, Ar: −186°C, Kr: −153°C, Xe: −108°C.

Larger atoms have stronger LONDON DISPERSION FORCES between them (a type of intermolecular force caused by temporary dipoles in electron clouds).

More electrons → greater temporary dipoles → stronger forces → higher boiling point.

DENSITY increases down the group.

The reactivity stays VERY LOW throughout — all noble gases are essentially inert under normal conditions.

⚠️ Common Mistake

Noble gases are MONATOMIC — they exist as single atoms (He, Ne, Ar) — NOT as molecules (not He₂ or Ne₂). This is because they are already stable with full outer shells and have no reason to form bonds. Other non-metals like oxygen (O₂) and nitrogen (N₂) exist as diatomic molecules because they share electrons to achieve full outer shells.

📌 Key Note

Noble gases: Group 0, full outer shells, extremely unreactive, monatomic. Boiling point increases down group (bigger atoms, stronger London dispersion forces). Helium: 2 outer electrons (full 1st shell). All others: 8 outer electrons (full outer shell).

🎯 Matching Activity — Match the Noble Gas Property

Match each property to noble gases and explain why. — drag the symbols on the right to match the component names on the left.

Very unreactive

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Monatomic

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Boiling point increases down group

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Colourless gases

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Helium — lighter than air

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Larger atoms have stronger London dispersion forces — more electrons, larger temporary dipoles

Full outer electron shells — no tendency to gain, lose or share electrons

Exist as single atoms — already stable, no need to bond with other atoms

Helium has only 2 electrons and 2 protons — very low density, used in balloons

All noble gases are transparent and gaseous at room temperature

🎯 Test Yourself

Question 1 of 2

1. Why are noble gases so unreactive?

2. Argon has a higher boiling point than neon. Why?

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🧪 Group 0 — Noble Gases

Properties of the Noble Gases

Why Noble Gases Are Unreactive

Trends Down Group 0

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