A Level H2 Chemistry Atomic Structure Bonding Quiz

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A-Level Chemistry H2 Quiz - Atomic Structure Bonding

Name: ________________________
Class: ________________________
Date: ________________________
Score: _______ / 40

Duration: 60 minutes
Total Marks: 40

Instructions:

• Answer all 20 questions.
• Section A: Multiple-choice style short items (1–5).
• Section B: Structured short-answer questions (6–15).
• Section C: Data interpretation and extended response (16–20).
• Show all working where calculations are required.
• Use the Data Booklet where relevant.

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Section A (Questions 1–5, 1 mark each, Total 5 marks)

1. An atom of isotope (^{37}{17}\text{Cl}) contains 20 neutrons. How many electrons does a neutral atom of (^{35}{17}\text{Cl}) have?

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2. Which type of orbital has a dumbbell shape?
   A. s
   B. p
   C. d
   D. f

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3. The first ionisation energy is defined as the energy required to remove one electron from ______________ in the gaseous state.

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4. In a σ (sigma) bond formed by overlap of two s orbitals, the electron density lies ________________________ the nuclei.

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5. Which intermolecular force is present between all molecules, polar or non-polar?
   A. Hydrogen bonding
   B. Permanent dipole–dipole
   C. Induced dipole–induced dipole
   D. Ionic bonding

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Section B (Questions 6–15, marks as stated, Total 20 marks)

6. [2 marks] Deduce the numbers of protons, neutrons, and electrons in the ion (^{27}\text{Al}^{3+}).
   Protons: _______
   Neutrons: _______
   Electrons: _______

7. [2 marks] Write the full electronic configuration of a neutral nitrogen atom (Z = 7).

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8. [2 marks] State the shape and bond angle of (\text{BF}_3) according to VSEPR theory.
   Shape: ________________________
   Bond angle: ________________________

9. [2 marks] Draw a dot-and-cross diagram for (\text{CO}_2). Show only outer-shell electrons of C and O.

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10. [2 marks] Explain why (\text{NH}_3) (ammonia) is a polar molecule although it contains polar N–H bonds.

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11. [2 marks] Describe the bonding in metallic sodium.

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12. [2 marks] State the type of bonding present in solid (\text{MgO}) and name the particles responsible for electrical conductivity in the molten state.
    Bonding: ________________________
    Conducting particles: ________________________

13. [2 marks] Compare the boiling points of (\text{H}_2\text{O}) and (\text{H}_2\text{S}). Explain your answer with reference to intermolecular forces.

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14. [2 marks] The bond energy of C–C is approximately 347 kJ mol⁻¹ and C=C is 614 kJ mol⁻¹. Which bond is shorter? Explain.

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15. [2 marks] Deduce whether (\text{CCl}_4) is polar or non-polar. Use bond polarity and molecular shape in your answer.

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Section C (Questions 16–20, marks as stated, Total 15 marks)

16. [3 marks] The successive ionisation energies (kJ mol⁻¹) of element X are:
    1st: 738, 2nd: 1451, 3rd: 7733, 4th: 10540.
    (a) Deduce the group of X in the Periodic Table.
    (b) Write the formula of the ion formed when X loses its valence electrons.
    (a) ________________________
    (b) ________________________

17. [3 marks] Given the following electronegativity values: H = 2.1, Cl = 3.0, C = 2.5, O = 3.5.
    (a) Which bond is most polar: C–H, C–Cl, or C–O?
    (b) State the direction of the dipole in C–O (show δ+ and δ–).
    (a) ________________________
    (b) ________________________

18. [3 marks] The table shows melting points of four substances.

Substance	Melting point / °C	Structure type
A	−182	simple molecular
B	801	ionic
C	3550	giant molecular
D	98	metallic

Explain why substance C has a much higher melting point than substance A.  
________________________________________________________  
________________________________________________________  
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19. [3 marks] Describe how a dative (coordinate) bond is formed in (\text{NH}_4^+). Include the origin of the electron pair.
________________________________________________________
________________________________________________________
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20. [3 marks] The first ionisation energies of Ne, Na, and Mg are 2081, 496, and 738 kJ mol⁻¹ respectively. Explain the trend from Ne to Na to Mg in terms of nuclear charge and electron shielding.

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A-Level Chemistry H2 Quiz - Atomic Structure Bonding (Answer Key)

Total Marks: 40
Topic: Atomic Structure & Bonding

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Section A Answers (5 marks)

Q1. [1 mark]
Answer: 17 electrons.
Teaching note: (^{35}_{17}\text{Cl}) has proton number 17. A neutral atom has electrons = protons = 17. The isotope mass (35 vs 37) changes neutron count only, not electrons.

Q2. [1 mark]
Answer: B (p).
Teaching note: s orbitals are spherical; p orbitals are dumbbell-shaped; d orbitals are cloverleaf-like.

Q3. [1 mark]
Answer: a gaseous atom (or "one mole of gaseous atoms").
Teaching note: First IE = energy to remove 1 electron from each atom in 1 mol of gaseous atoms: (\text{X(g)} \rightarrow \text{X}^+(g) + e^-).

Q4. [1 mark]
Answer: along the axis between (or "directly between").
Teaching note: A σ bond from s–s overlap has cylindrical symmetry about the internuclear axis; electron density is between nuclei.

Q5. [1 mark]
Answer: C (induced dipole–induced dipole / London dispersion).
Teaching note: All molecules exhibit temporary induced dipoles; H-bonding and permanent dipoles require specific conditions.

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Section B Answers (20 marks)

Q6. [2 marks]

• Protons: 13 (from Z = 27, Al has Z=13)
• Neutrons: 27 − 13 = 14
• Electrons: 13 − 3 = 10 (3+ charge means loss of 3 e⁻)
  Marking: 1 mark for protons/neutrons correct pair, 1 mark for electrons.

Q7. [2 marks]
Answer: (1s^2 2s^2 2p^3)
Teaching note: Z=7 → 7 electrons fill 1s (2), 2s (2), 2p (3). Award 1 mark for correct order, 1 for superscript counts.

Q8. [2 marks]
Shape: trigonal planar
Bond angle: 120°
Teaching note: B has 3 bond pairs, 0 lone pairs → AX₃ → trigonal planar, 120°.

Q9. [2 marks]
Dot-and-cross: O=C=O with double bonds; C shares 4 e⁻ (2 from each O). Expected:
:O::C::O: (using cross for C, dot for O outer e⁻)
Marking: 1 for two double bonds, 1 for correct octets.

Q10. [2 marks]
Answer: N–H bonds are polar (N more electronegative). Molecular shape is trigonal pyramidal (one lone pair on N), so bond dipoles do not cancel → net dipole.
Marking: 1 for shape/lone pair, 1 for non-cancellation.

Q11. [2 marks]
Answer: Delocalised valence electrons in a 'sea' around positive metal ions (Na⁺); electrostatic attraction holds lattice.
Marking: 1 for delocalised electrons, 1 for electrostatic attraction.

Q12. [2 marks]
Bonding: ionic
Conducting particles: Mg²⁺ and O²⁻ (ions)
Marking: 1 each.

Q13. [2 marks]
Answer: H₂O has higher bp than H₂S because H₂O forms hydrogen bonds (O–H), stronger than induced dipoles in H₂S.
Marking: 1 for comparison, 1 for H-bond reason.

Q14. [2 marks]
Answer: C=C is shorter. Higher bond energy means stronger attraction → shorter bond.
Marking: 1 for C=C, 1 for explanation.

Q15. [2 marks]
Answer: Non-polar. C–Cl bonds are polar but tetrahedral shape causes dipoles to cancel.
Marking: 1 for non-polar, 1 for symmetry cancellation.

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Section C Answers (15 marks)

Q16. [3 marks]
(a) Group 2 (large jump after 2nd IE). [2 marks]
(b) X²⁺ [1 mark]
Teaching note: Big increase 3rd IE → 2 valence e⁻ removed → Group 2.

Q17. [3 marks]
(a) C–O (ΔEN = 1.0 > C–Cl 0.5 > C–H 0.4). [2 marks]
(b) Cδ+ – Oδ− [1 mark]
Teaching note: Higher EN gets δ−.

Q18. [3 marks]
Answer: C is giant molecular (e.g. diamond) with strong covalent network needing much energy to break; A is simple molecular with weak induced dipoles. [3 marks: 1 structure, 1 forces, 1 comparison]

Q19. [3 marks]
Answer: NH₃ donates lone pair on N to H⁺ (no e⁻); both e⁻ in N–H bond from N. [3: 1 donation, 1 origin, 1 bond formed]

Q20. [3 marks]
Ne high IE (full shell). Na low (new shell, shielding). Mg higher than Na (higher Z, same shell). [3: 1 Ne, 1 Na drop, 1 Mg rise]