Cambridge IGCSE Chemistry 0620

8.5.2 — Noble Gases: Past Paper Exam

Papers 3 & 4 | Group VIII (Group 0) | Unreactivity & Electronic Structure

Total Marks

Helium

Neon

Argon

🔑 The Golden Rule: Noble gases are unreactive because their outer electron shells are completely full. They have no tendency to gain, lose, or share electrons.

Section A: Properties

[1 mark]

State the general reactivity of the Group VIII (Group 0) elements.

💡 Hint: Think about what makes them special compared to all other groups.

[1 mark]

State whether noble gases exist as monatomic or diatomic particles, and give a reason.

💡 Hint: Compare to H₂ and O₂ — are noble gases similar?

[2 marks]

Give TWO physical properties of the noble gases as a group.

💡 Hint: Think about their state at room temperature and their boiling points.

[1 mark]

Describe the trend in boiling point of the noble gases as you go down Group VIII (from Helium to Radon).

💡 Hint: As atoms get bigger, what happens to the forces between them?

[2 marks]

Give ONE use of Helium and ONE use of Argon. Link each use to a property of the gas.

💡 Hint: Why do we fill balloons with helium? Why do we use argon in lightbulbs?

Section B: The Explanation

[2 marks]

Explain, in terms of electronic configuration, why Neon (atomic number 10) is unreactive.

💡 Hint: Draw out neon's electron shells: 2, 8. What does that tell you?

[2 marks]

Explain why Helium (atomic number 2) is unreactive, despite only having ONE electron shell.

💡 Hint: Helium's first shell can hold a maximum of 2 electrons. How many does it have?

[3 marks]

Using your knowledge of electronic configurations, explain why the reactivity of Group I elements (like Sodium) contrasts sharply with the unreactivity of noble gases like Argon.

💡 Hint: Compare their outer shells. One is incomplete, one is complete.

[2 marks]

A student claims: 'Noble gases are unreactive because they have no electrons.' Identify the error in this statement and write a correct explanation.

💡 Hint: Do noble gases literally have zero electrons? Check the atomic number of Helium (2) and Neon (10).

Q10

[2 marks]

Krypton (Kr) has an atomic number of 36 and an electronic configuration of 2,8,18,8. Explain why Krypton is unreactive.

💡 Hint: Focus on the OUTERMOST shell only.

Section C: Comparisons

Q11

[2 marks]

Contrast the particle structure of Helium gas with Hydrogen gas.

💡 Hint: How many atoms in each particle? What does 'monatomic' vs 'diatomic' mean?

Q12

[2 marks]

Compare the chemical reactivity of the noble gases with the elements in Group VII (the Halogens). Explain why they differ.

💡 Hint: How many electrons does a halogen have in its outer shell? How many does a noble gas have?

Q13

[2 marks]

State TWO similarities and ONE difference between Neon and Argon.

💡 Hint: Think about physical properties and uses.

Q14

[3 marks]

Neon is used in advertising signs and Argon is used in light bulbs. For EACH use, explain which property of the noble gas makes it suitable, and why that property arises from its electronic structure.

💡 Hint: Two uses = two separate explanations. Link property → electronic structure for each.

Q15Supplement

[3 marks]

[EXTENDED] Explain why the boiling points of noble gases increase from Helium to Radon, making reference to the forces between atoms and atomic size.

💡 Hint: This is a Supplement-level question. Think about London dispersion forces and how they scale with atomic size.

📋 Exam Reference: Noble Gas Electronic Configurations

Element	Symbol	Atomic No.	Configuration	Outer Shell
Helium	He	2	2	2 (FULL — max 2)
Neon	Ne	10	2, 8	8 (FULL)
Argon	Ar	18	2, 8, 8	8 (FULL)
Krypton	Kr	36	2, 8, 18, 8	8 (FULL)
Xenon	Xe	54	2, 8, 18, 18, 8	8 (FULL)
Radon	Rn	86	2, 8, 18, 32, 18, 8	8 (FULL)

All noble gases have FULL outer electron shells → All are unreactive / inert

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