Structure, Bonding & the Properties of MatterOxford AQA IGCSE Chemistry: Topic test

20 questions, 54 marks

Oxford AQA IGCSE Chemistry

Structure, Bonding & the Properties of Matter topic test

Total 54 marks

Name

Class

Date

1
Magnesium reacts with chlorine gas to form magnesium chloride, MgCl₂, in which magnesium ions and chloride ions are held together by ionic bonds.
(a)
What is the charge on a magnesium ion in this compound?
[1 mark]
A2+
B1+
C2−
D1−
(b)
How many electrons does one magnesium atom transfer, and to how many chlorine atoms, when magnesium chloride forms?
[1 mark]
ATwo electrons, both to a single chlorine atom
BOne electron to each of two separate chlorine atoms
CNo electrons; the atoms share a pair of electrons instead
DThree electrons, one to each of three chlorine atoms
(c)
Explain, in terms of electron transfer, how the ionic bond in magnesium chloride forms.
[2 marks]
Total for question 1: 4 marks
2
Hydrogen gas reacts with chlorine gas to form hydrogen chloride gas, HCl, in which each molecule is held together by a covalent bond.
(a)
What type of bond forms between the hydrogen atom and the chlorine atom in a molecule of hydrogen chloride?
[1 mark]
AAn ionic bond, formed by electron transfer
BA metallic bond, formed by delocalised electrons
CA covalent bond, formed by a shared pair of electrons
DNo bond forms; the atoms are held together only by weak forces
(b)
Why do the hydrogen and chlorine atoms share electrons rather than transfer them completely?
[1 mark]
ABecause hydrogen and chlorine are both metals
BBecause sharing releases more energy than transferring in every reaction
CBecause hydrogen has no electrons available to transfer
DBecause both atoms are non-metals, so sharing a pair of electrons allows each atom to gain a full, stable outer shell without either atom fully gaining or losing an electron
(c)
Describe how a covalent bond forms between the hydrogen atom and the chlorine atom in a molecule of hydrogen chloride.
[2 marks]
Total for question 2: 4 marks
3
A technician compares two unlabelled solid compounds, X and Y. Compound X melts at −95°C and boils at 12°C, and is made up of individual molecules. Compound Y does not melt until 1450°C, and every atom in its structure is linked to its neighbours by covalent bonds throughout the solid.
(a)
Explain, in terms of bonding and structure, why compound X has such a low melting and boiling point compared with compound Y.
[3 marks]
(b)
Both compound X and compound Y fail to conduct electricity in any state. Explain why neither compound conducts electricity, even though they have very different structures.
[4 marks]
Total for question 3: 7 marks
4
A materials engineer tests three unlabelled solid samples, P, Q and R, at room temperature. Sample P does not conduct electricity as a solid, but does conduct when melted or dissolved in water. Sample Q does not conduct electricity in any state, solid, liquid or gas. Sample R conducts electricity as a solid and can be hammered into a new shape without shattering.
(a)
Identify the type of bonding present in each of samples P, Q and R, giving a reason for each identification based on the evidence described.
[6 marks]
(b)
Sample R can be bent and reshaped without breaking, but a typical ionic compound shatters when struck with a hammer. Explain, in terms of structure and bonding, why sample R behaves so differently from an ionic compound when force is applied, and predict which of samples P and R is likely to have the higher melting point, giving a reason.
[6 marks]
Total for question 4: 12 marks
5
A chemical engineering team is developing a new industrial catalyst made from buckminsterfullerene (C₆₀) cage molecules, each built from a network of hexagonal rings of carbon atoms, with small amounts of a metal attached to their surface. The catalyst is added to speed up a reaction inside a large chemical reactor.
(a)
What is the basic structure of a buckminsterfullerene molecule?
[1 mark]
AA hollow, roughly spherical cage of 60 carbon atoms arranged in hexagonal rings
BA flat sheet of carbon atoms arranged in a single hexagonal layer
CA giant lattice in which every carbon atom is bonded to four others
DA long, straight chain of carbon atoms with no rings
(b)
What property makes fullerene-based catalysts especially useful?
[1 mark]
AThey react completely and are used up during the reaction
BTheir cage-like structure gives a very large surface area for the reaction to take place on, without the catalyst itself being used up
CThey are ionic, so they conduct electricity during the reaction
DThey melt at a very low temperature, which speeds up melting-based reactions
(c)
Explain why attaching the catalyst to fullerene cages, rather than using it as a solid lump, allows the reaction to proceed faster.
[2 marks]
Total for question 5: 4 marks
6
A construction company is testing a new paint additive containing zinc oxide nanoparticles, each between 1 and 100 nm in size, added to exterior paint to make painted surfaces resist UV damage and stay cleaner for longer.
(a)
What size range defines a nanoparticle?
[1 mark]
A1–100 mm
B1–100 µm
C1–100 nm
D1–100 m
(b)
Why might these zinc oxide nanoparticles behave differently from bulk (large-scale) zinc oxide?
[1 mark]
ANanoparticles are a completely different chemical element from bulk zinc oxide
BNanoparticles have a lower melting point purely because they contain fewer atoms overall
CNanoparticles cannot form chemical bonds with other substances
DNanoparticles have a much higher surface area to volume ratio than the same mass of bulk material, which changes their properties
(c)
Explain why a high surface area to volume ratio makes nanoparticles more effective in this paint additive than an equivalent mass of bulk zinc oxide powder.
[2 marks]
Total for question 6: 4 marks
7
A lighting engineer selects tungsten metal to make the glowing filament inside an incandescent lightbulb, because the filament must withstand extremely high temperatures without melting while still conducting electricity efficiently, and must be drawn into a very thin wire without breaking.
(a)
Explain, in terms of metallic bonding, why tungsten is able to conduct electricity efficiently.
[3 marks]
(b)
Explain why tungsten wire can be drawn out into a very thin filament without breaking, and contrast this with the behaviour of a typical ionic compound when force is applied to it.
[4 marks]
Total for question 7: 7 marks
8
A tool manufacturer is developing two new products at the same time: a coating for the cutting edge of a high-precision drill bit, which must be extremely hard and wear-resistant, and a dry lubricant powder to reduce friction between moving machine parts, both to be made from different forms of carbon, diamond and graphite.
(a)
Explain, in terms of structure and bonding, why diamond is suitable for the drill-bit coating.
[6 marks]
(b)
Explain, in terms of structure and bonding, why graphite, despite also being a form of carbon, is suitable as a dry lubricant rather than a hard cutting material.
[6 marks]
Total for question 8: 12 marks

End of questions