2022 May/June · Paper 43 · Q5 (a)3 marksMetallic bonding
No questions match this filter.
References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Atomic structure & isotopes · Core · Paper 2 style · 1 mark
(a)An ion of iron is written as ⁵⁶₂₆Fe³⁺. How many protons, neutrons and electrons does this ion contain?[1]
Show answer
(a) A 26 protons, 30 neutrons, 23 electrons
Proton number 26; neutrons = 56 − 26 = 30; a 3+ ion has lost 3 electrons, so 26 − 3 = 23. B adds 3 electrons instead of removing them.
Q2Atomic structure & isotopes · Core · Paper 4 style · 4 marks
(a)Complete the following: an atom has a central ______ containing protons and ______, surrounded by ______ in shells.[2]
(b)Give the electronic configuration of a magnesium atom (proton number 12).[1]
(c)Magnesium has three isotopes. State why all three isotopes react in the same way with dilute hydrochloric acid.[1]
Show answer
(a) nucleus; neutrons; electrons
2 marks for all three correct, 1 mark for two correct.
(b) 2,8,2
(c) They have the same number of outer-shell electrons / the same electronic configuration.
Chemical properties depend on electrons, not neutrons.
Q3Atomic structure & isotopes · Core · Paper 4 style · 4 marks
(a)Give the relative mass and relative charge of: (i) a proton, (ii) a neutron, (iii) an electron.[3]
(b)State which two of these particles are found in the nucleus.[1]
Show answer
(a) proton: mass 1, charge +1; neutron: mass 1, charge 0; electron: mass 1/1840 (negligible), charge −1
1 mark for each particle with both values correct.
(b) protons and neutrons
Q4Atomic structure & isotopes · Core · Paper 4 style · 4 marks
Phosphorus is one of the three main nutrient elements in fertilisers used on wheat farms in Punjab. A phosphorus atom has 15 electrons.
(a)Give the electronic configuration of a phosphorus atom.[1]
(b)Use your answer to (a) to state the group and the period of phosphorus in the Periodic Table.[2]
(c)State the number of protons in the nucleus of a phosphorus atom.[1]
Show answer
(a) 2,8,5
(b) Group V; Period 3
B1 group V (5 outer electrons); B1 period 3 (three shells).
(c) 15
Proton number = 15.
Q5Atomic structure & isotopes · Standard · Paper 4 style · 5 marks
Gallium is used in semiconductors for LED lights. A sample of gallium contains 60.1 % of gallium-69 and 39.9 % of gallium-71.
(a)Explain what is meant by the term isotopes.[2]
(b)Calculate the relative atomic mass of gallium. Give your answer to 1 decimal place.[2]
(c)State the number of neutrons in one atom of gallium-71 (proton number 31).[1]
Show answer
(a) Atoms of the same element (same number of protons / same proton number) with different numbers of neutrons (different nucleon numbers).
B1 same proton number / same element; B1 different number of neutrons.
Q6Atomic structure & isotopes · Standard · Paper 2 style · 1 mark
(a)Which pair of atoms are isotopes of the same element? (Values given as nucleon number, proton number.)[1]
Show answer
(a) B (35, 17) and (37, 17)
Isotopes have the same proton number but different nucleon numbers: 17 and 17 with 35 and 37. A has the same nucleon number but different proton numbers, so they are different elements.
Q7Atomic structure & isotopes · Standard · Paper 4 style · 5 marks
(a)Particle X has 17 protons, 20 neutrons and 18 electrons. Write the symbol of X, showing its nucleon number and charge.[2]
(b)Particle Y has 12 protons, 12 neutrons and 10 electrons. Write the symbol of Y, showing its nucleon number and charge.[2]
(c)Give the electronic configuration of a sulfide ion, S²⁻ (proton number of sulfur 16).[1]
Show answer
(a) ³⁷Cl⁻
B1 Cl with nucleon number 37; B1 charge 1− (one more electron than protons).
(b) ²⁴Mg²⁺
B1 Mg with nucleon number 24; B1 charge 2+.
(c) 2,8,8
16 + 2 = 18 electrons.
Q8Atomic structure & isotopes · Challenge · Paper 4 style · 4 marks
Boron compounds are used in heat-resistant glass. Natural boron is a mixture of only two isotopes, boron-10 and boron-11. The relative atomic mass of boron is 10.81.
(a)Let the percentage of boron-10 be x. Write an expression for the relative atomic mass of boron in terms of x.[1]
(b)Calculate the percentage of boron-10 atoms in natural boron.[2]
(c)Calculate the number of neutrons in an atom of boron-11. The proton number of boron is 5.[1]
Show answer
(a) [10x + 11(100 − x)] ÷ 100
(b) 19 %
M1 10x + 1100 − 11x = 1081, so x = 19; A1 19 %.
(c) 6
11 − 5 = 6.
Q9Atomic structure & isotopes · Challenge · Paper 4 style · 5 marks
A mass spectrometer in a university laboratory in Islamabad gives these results for a sample of magnesium:magnesium-24: 78.99 %magnesium-25: 10.00 %magnesium-26: 11.01 %
(a)Calculate the relative atomic mass of magnesium. Give your answer to 3 significant figures.[2]
(b)State the number of neutrons in one atom of magnesium-26. The proton number of magnesium is 12.[1]
(c)A student says that magnesium-26 must be more reactive than magnesium-24 because it is heavier. Explain why the student is wrong.[2]
(c) Both isotopes have 12 electrons with the same arrangement (2 outer electrons), and reactivity depends on the electrons, not on the number of neutrons.
B1 same electronic configuration / same number of outer electrons; B1 neutrons do not affect chemical reactions.
Q10Ions & ionic bonding · Core · Paper 2 style · 1 mark
(a)Calcium forms Ca²⁺ ions and nitrogen forms N³⁻ ions. What is the formula of calcium nitride?[1]
Show answer
(a) C Ca₃N₂
Charges must balance: 3 × (+2) = +6 and 2 × (−3) = −6, so Ca₃N₂. B swaps the numbers the wrong way round.
Q11Ions & ionic bonding · Core · Paper 4 style · 5 marks
(a)Give the electronic configurations of a lithium atom and a fluorine atom.[2]
(b)Give the formulae, with charges, of the two ions in lithium fluoride.[2]
(c)Name the type of bonding in lithium fluoride.[1]
Show answer
(a) Li 2,1; F 2,7
1 mark each.
(b) Li⁺ and F⁻
(c) ionic
Q12Ions & ionic bonding · Standard · Paper 4 style · 5 marks
Magnesium oxide is used to line the inside of furnaces in steel works.
(a)Describe, in terms of electrons, how a magnesium atom and an oxygen atom form magnesium oxide. Give the electronic configurations of both ions formed.[3]
(b)Explain why magnesium oxide has a very high melting point.[2]
Show answer
(a) Magnesium atom loses its two outer electrons, oxygen atom gains two electrons; Mg²⁺ is 2,8 and O²⁻ is 2,8.
B1 two electrons transferred from Mg to O; B1 Mg²⁺ 2,8; B1 O²⁻ 2,8.
(b) It has a giant ionic lattice with strong electrostatic attraction between oppositely charged ions; a lot of energy is needed to overcome these forces.
B1 strong electrostatic attraction between oppositely charged ions; B1 lots of energy needed to overcome them / giant lattice.
Q13Ions & ionic bonding · Standard · Paper 2 style · 1 mark
(a)Which ions all have the same electronic configuration as a neon atom?[1]
Show answer
(a) C Na⁺, Al³⁺, O²⁻
Na⁺, Al³⁺ and O²⁻ each have 10 electrons (2,8). A includes Cl⁻ (2,8,8); D are all 2,8,8 like argon; Li⁺ in B is 2.
Q14Ions & ionic bonding · Standard · Paper 4 style · 4 marks
(a)Give the formula of aluminium oxide, which contains Al³⁺ and O²⁻ ions.[1]
(b)Calculate the total number of electrons transferred when the ions in one formula unit of aluminium oxide are formed from atoms.[2]
(c)Give the formula of potassium sulfide.[1]
Show answer
(a) Al₂O₃
(b) 6
M1 each Al loses 3 electrons and there are 2 Al; A1 6 (= 3 O atoms × 2 electrons).
(c) K₂S
K⁺ and S²⁻.
Q15Ions & ionic bonding · Challenge · Paper 4 style · 6 marks
(a)Explain why solid sodium chloride does not conduct electricity but molten sodium chloride does.[2]
(b)The melting point of sodium chloride is 801 °C and the melting point of magnesium oxide is 2852 °C. Suggest why the melting point of magnesium oxide is much higher.[2]
(c)Describe the structure of solid sodium chloride.[2]
Show answer
(a) In the solid the ions are held in fixed positions in the lattice and cannot move; when molten the ions are free to move and carry charge.
B1 ions fixed in solid; B1 ions mobile when molten. (Reject 'electrons move'.)
(b) Mg²⁺ and O²⁻ have larger charges than Na⁺ and Cl⁻, so the electrostatic attraction between the ions is stronger and needs more energy to overcome.
B1 ions have charges 2+ / 2− compared with 1+ / 1−; B1 stronger attraction, more energy needed.
(c) A giant lattice of alternating Na⁺ and Cl⁻ ions in a regular repeating arrangement.
B1 giant lattice; B1 regular alternating positive and negative ions.
Q16Simple covalent molecules · Core · Paper 4 style · 4 marks
Ammonia is used to make urea fertiliser at plants near Daharki.
(a)In an ammonia molecule, NH₃, state the number of bonding pairs of electrons and the number of non-bonding (lone) pairs on the nitrogen atom.[2]
(b)Ammonia boils at −33 °C. Explain, in terms of forces, why ammonia has a low boiling point.[2]
(b) The intermolecular forces between ammonia molecules are weak, so little energy is needed to separate the molecules.
B1 weak intermolecular forces / forces between molecules; B1 little energy needed. Reject 'weak covalent bonds'.
Q17Simple covalent molecules · Core · Paper 4 style · 4 marks
(a)When iodine crystals are warmed gently in a boiling tube, a purple vapour forms. Name the type of structure in solid iodine.[1]
(b)Explain why iodine changes to a vapour at a low temperature.[2]
(c)Predict whether solid iodine conducts electricity. Give a reason.[1]
Show answer
(a) simple molecular (simple covalent molecules of I₂)
(b) The forces between I₂ molecules are weak intermolecular forces, which need little energy to overcome.
B1 weak intermolecular forces; B1 little energy needed.
(c) No, it has no ions or free electrons to carry charge.
Q18Simple covalent molecules · Standard · Paper 2 style · 1 mark
(a)How many electrons are shared between the atoms in one molecule of carbon dioxide, O=C=O?[1]
Show answer
(a) C 8
There are two double bonds; each double bond is 2 shared pairs = 4 electrons, so 2 × 4 = 8. A counts only the number of shared pairs.
Q19Simple covalent molecules · Standard · Paper 4 style · 4 marks
(a)State the total number of covalent bonds in one molecule of methanol, CH₃OH.[1]
(b)State the number of non-bonding pairs of electrons on the oxygen atom in methanol.[1]
(c)Explain why liquid methanol does not conduct electricity.[2]
Show answer
(a) 5
3 C–H, 1 C–O, 1 O–H.
(b) 2
O has 6 outer electrons, 2 used in bonds.
(c) It is made of neutral molecules; there are no ions or free (delocalised) electrons to carry charge.
B1 molecules / no ions; B1 no mobile charged particles.
Q20Simple covalent molecules · Challenge · Paper 4 style · 5 marks
(a)A nitrogen molecule contains a triple bond. State the number of electrons shared between the two atoms and the number of non-bonding pairs on each nitrogen atom.[2]
(b)A student writes: 'When liquid nitrogen boils, the covalent bonds between the nitrogen atoms break.' Explain why this statement is incorrect.[2]
(c)Suggest why nitrogen gas is very unreactive.[1]
Show answer
(a) 6 shared electrons; 1 non-bonding pair on each N
B1 6; B1 one lone pair each.
(b) Boiling only overcomes the weak intermolecular forces between N₂ molecules; the covalent (triple) bonds inside each molecule are not broken.
(c) The N≡N triple bond is very strong and needs a lot of energy to break.
Q21Giant covalent structures · Core · Paper 4 style · 5 marks
(a)Describe the structure of diamond.[2]
(b)Use the structure of diamond to explain why it is used in drill tips for oil wells.[1]
(c)Graphite is used in pencils. Explain, in terms of its structure, why graphite is soft.[2]
Show answer
(a) Each carbon atom is covalently bonded to four other carbon atoms in a giant three-dimensional (tetrahedral) lattice.
B1 each C bonded to 4 others; B1 giant 3-D covalent lattice.
(b) It is very hard because of many strong covalent bonds in a giant structure.
(c) Graphite has layers of carbon atoms with weak forces between the layers, so the layers slide over each other.
B1 layers; B1 weak forces between layers so layers slide.
Q22Giant covalent structures · Standard · Paper 2 style · 1 mark
(a)Which statement about silicon(IV) oxide, SiO₂, is correct?[1]
Show answer
(a) B Each silicon atom is bonded to four oxygen atoms and each oxygen atom to two silicon atoms.
SiO₂ is a giant covalent lattice: Si bonded to 4 O, each O to 2 Si, giving the 1 : 2 ratio. A describes a simple molecular structure like CO₂, which SiO₂ is not.
Q23Giant covalent structures · Challenge · Paper 4 style · 5 marks
(a)Explain why graphite conducts electricity but diamond does not.[2]
(b)State one similarity in the structure of diamond and silicon(IV) oxide.[1]
(c)Explain why both diamond and silicon(IV) oxide have very high melting points.[2]
Show answer
(a) In graphite each carbon uses only three outer electrons in bonding, so one electron per atom is delocalised and can move; in diamond all four outer electrons are in covalent bonds.
B1 graphite has delocalised / mobile electrons (one per C); B1 diamond: all 4 electrons used in bonds, none free.
(b) Both are giant covalent (macromolecular) structures with every atom held by strong covalent bonds in 3-D.
Accept: both have tetrahedral arrangement around the central atom.
(c) Many strong covalent bonds must be broken to melt them; this needs a lot of energy.
B1 many strong covalent bonds; B1 must be broken, needing much energy.
Q24Structure and properties compared · Core · Paper 4 style · 5 marks
(a)Sodium chloride is a solid at room temperature but hydrogen chloride is a gas. State the type of bonding in each compound.[2]
(b)Explain the difference in their states at room temperature.[3]
(b) Sodium chloride has a giant lattice with strong electrostatic attraction between ions, needing much energy to break; hydrogen chloride is made of small molecules with weak intermolecular forces, needing little energy to separate.
B1 NaCl giant ionic lattice, strong forces between ions; B1 HCl simple molecules, weak intermolecular forces; B1 comparison of energy needed.
Q25Structure and properties compared · Standard · Paper 4 style · 6 marks
Properties of four substances:W: melting point 801 °C; conducts when solid: no; when molten: yes; dissolved in water: yesX: melting point −95 °C; conducts when solid: no; when liquid: no; insoluble in waterY: melting point 1083 °C; conducts when solid: yes; when molten: yes; insoluble in waterZ: melting point 1710 °C; conducts when solid: no; when molten: no; insoluble in water
(a)Identify the type of structure in each of W, X, Y and Z. Choose from: giant ionic, simple molecular, giant metallic, giant covalent.[4]
(b)Explain why W conducts electricity when dissolved in water but not when solid.[2]
Show answer
(a) W giant ionic; X simple molecular; Y giant metallic; Z giant covalent
1 mark each.
(b) In solution its ions are free to move; in the solid the ions are fixed in the lattice.
B1 ions move in solution; B1 ions fixed in solid.
Q26Structure and properties compared · Challenge · Paper 4 style · 5 marks
(a)Carbon and silicon are both in Group IV. Carbon dioxide turns directly to a gas at −78 °C, but silicon(IV) oxide melts at about 1700 °C. Explain this difference in terms of structure and bonding.[4]
(b)Predict whether silicon(IV) oxide conducts electricity when molten. Give a reason.[1]
Show answer
(a) CO₂ is simple molecular: weak intermolecular forces between CO₂ molecules are overcome, needing little energy. SiO₂ is giant covalent: many strong covalent bonds between Si and O atoms must be broken, needing much energy.
Q27Metallic bonding · Core · Paper 4 style · 3 marks
(a)Describe metallic bonding.[2]
(b)Explain why metals are good electrical conductors.[1]
Show answer
(a) A lattice of positive metal ions in a 'sea' of delocalised electrons; held together by electrostatic attraction between the positive ions and the delocalised electrons.
B1 lattice of positive ions and delocalised electrons; B1 electrostatic attraction between them.
(b) The delocalised electrons can move through the structure and carry charge.
Q28Metallic bonding · Standard · Paper 4 style · 5 marks
(a)Copper is used for electrical wiring in houses. Explain in terms of structure why copper can be drawn into wires and why it conducts electricity.[3]
(b)Explain why copper has a high melting point.[2]
Show answer
(a) Layers of copper ions can slide over each other (ductile); delocalised electrons move through the lattice and carry charge.
B1 layers slide; B1 bonding not broken as layers slide / structure stays together; B1 delocalised electrons move.
(b) Strong electrostatic attraction between positive copper ions and delocalised electrons; much energy needed to overcome it.
B1 strong attraction ions–electrons; B1 much energy needed.
Q29Metallic bonding · Challenge · Paper 4 style · 4 marks
(a)Explain why metals such as aluminium can be hammered into thin sheets (are malleable).[2]
(b)The melting point of sodium is 98 °C and that of magnesium is 650 °C. Suggest why magnesium has the higher melting point.[2]
Show answer
(a) The layers of positive ions can slide over each other while the delocalised electrons keep holding the structure together, so the metal changes shape without breaking.
B1 layers of ions slide; B1 metallic bonding not broken / electrons still hold layers.
(b) Magnesium ions are Mg²⁺ (higher charge) and each atom gives two delocalised electrons, so the attraction between the ions and the delocalised electrons is stronger.
B1 Mg²⁺ / more delocalised electrons per atom; B1 stronger electrostatic attraction, more energy needed.
Q30Elements, compounds & mixtures · Core · Paper 2 style · 1 mark
(a)Which of these is a mixture?[1]
Show answer
(a) B sea water
Sea water contains water with several dissolved salts that are not chemically combined, so it is a mixture. Distilled water and sodium chloride are compounds; copper is an element.
Similar questions
Questions that test the same subtopic in different years, grouped so you can work on one skill at a time.
References only: find each question in its paper (official link where available, otherwise through your school).
