Chemistry Year 11 Module 1 Lessons 16-20 ~20 min

Checkpoint Quiz 4

This checkpoint closes Module 1 with electron configuration, periodic trends and full-module synthesis. Attempt the multiple choice first, then self-assess the short answers against the model responses.

L16-L17

  • Write electron configurations using Aufbau, Pauli and Hund.
  • Explain atomic radius using shell number, shielding and effective nuclear charge.
  • Compare neutral atoms with cations and anions by radius.

L18-L20

  • Use electronegativity and reactivity trends correctly.
  • Predict likely ions from electron configuration and group position.
  • Link structure, bonding and properties in one chain of reasoning.

Attempt every question before opening the model answers. Feedback appears immediately for multiple choice.

Multiple Choice

1. Which is the correct electron configuration for sulfur, Z = 16?

A
1s² 2s² 2p⁴ 3s² 3p⁴
B
1s² 2s² 2p⁶ 3s⁴ 3p²
C
1s² 2s² 2p⁶ 3s² 3p⁴
D
1s² 2s² 2p⁶ 3s² 3p⁶

2. Which arrangement violates Hund's rule?

A
Three 2p orbitals each occupied singly before any pairing
B
Nitrogen written as [He]2s²2p³
C
Electrons spread across equal-energy p orbitals before doubling up
D
One p orbital doubly occupied while another equal-energy p orbital is still empty

3. Why does atomic radius generally decrease across a period?

A
The number of occupied shells decreases across the period
B
Proton number rises while electrons are added to the same main shell, increasing effective nuclear charge
C
Shielding increases dramatically and forces electrons inward
D
Atoms lose valence electrons across the period

4. Which species is larger?

A
Na⁺, because positive ions are larger than atoms
B
Na⁺, because it has fewer electrons to repel each other
C
Na, because forming Na⁺ removes the outer shell and reduces electron-electron repulsion
D
They are the same size because they have the same nucleus

5. Why is caesium more reactive than lithium as a metal?

A
Cs has higher electronegativity
B
Cs has more valence electrons available to lose
C
Cs is smaller, so its valence electron is easier to remove
D
Cs is further down Group 1, so its valence electron is further from the nucleus and more shielded

6. The bond between potassium and fluorine is best classified as:

A
Non-polar covalent
B
Ionic
C
Polar covalent
D
Metallic

7. Lithium and sodium show similar chemistry mainly because they:

A
Both have one valence electron and tend to form 1+ ions
B
Have the same atomic radius
C
Sit in the same period
D
Contain the same number of neutrons

8. An unknown solid has an extremely high melting point, does not conduct in any state, is insoluble and very hard. It is most likely:

A
A metallic solid
B
An ionic solid
C
A covalent network solid
D
A covalent molecular solid

9. HF has a much higher boiling point than HCl mainly because:

A
HF forms hydrogen bonds while HCl only has dipole-dipole and dispersion forces
B
HF is more acidic, which always raises boiling point
C
HF has stronger dispersion forces because fluorine is larger
D
HCl is ionic and therefore boils more easily

10. Graphene is exceptionally strong and electrically conductive because it has:

A
Ionic bonding in a 2D lattice
B
Metallic bonding in thin sheets
C
Weak dispersion forces between carbon atoms
D
Strong sp² covalent bonds in a hexagonal lattice plus delocalised electrons

Short Answer

11. Explain why chlorine is smaller than phosphorus even though both are in Period 3. 3 marks

Answer in your book

12. Copper can form both Cu⁺ and Cu²⁺, while sodium usually forms only Na⁺. Explain why. 4 marks

Answer in your book

13. A chemist concludes that an unknown substance is a covalent network solid rather than an ionic, metallic or molecular substance. Write a short justification using at least three properties. 4 marks

Answer in your book

Open Model Answers

▼

MC 1-10

1. C. 2. D. 3. B. 4. C. 5. D. 6. B. 7. A. 8. C. 9. A. 10. D.

Q11

Chlorine is smaller than phosphorus because both atoms have their valence electrons in the same main shell, so shielding is similar. Chlorine has more protons, giving it a higher effective nuclear charge. The stronger nuclear attraction pulls the outer electrons closer to the nucleus, reducing atomic radius.

Q12

Sodium has the configuration [Ne]3s¹, so losing one electron gives the very stable [Ne] arrangement. Removing a second electron would mean taking one from a full inner shell, which requires far more energy. Copper has accessible 4s and 3d electrons of similar energy, so it can lose the 4s electron to form Cu⁺ and, in many contexts, one additional 3d electron to form Cu²⁺. Transition metals therefore show more variable oxidation states than Group 1 metals.

Q13

A covalent network solid is justified by the combination of extremely high melting point, extreme hardness and insolubility. Those properties indicate a giant three-dimensional lattice of strong covalent bonds rather than discrete molecules. The lack of electrical conductivity rules out a metallic solid, and non-conductivity even when heated helps distinguish it from a typical ionic substance. The structure therefore best matches a covalent network solid such as diamond or silicon carbide.

Mark checkpoint as complete

Tick this once you have attempted the multiple choice and checked the model answers.