Bonding, Structure and the Properties of MatterAQA GCSE Chemistry: Topic test

20 questions, 54 marks

AQA GCSE Chemistry

Bonding, Structure and the Properties of Matter topic test

Total 54 marks

Name

Class

Date

1
A fertiliser company produces potassium chloride (potash), an ionic compound, and tests samples for melting point and electrical conductivity in solid, molten and dissolved states as part of its quality control before shipping to farms.
(a)
Potassium chloride is formed when a potassium atom reacts with a chlorine atom. What happens to the electrons during this reaction?
[1 mark]
AThe potassium atom transfers one electron to the chlorine atom
BThe potassium and chlorine atoms share a pair of electrons
CThe chlorine atom transfers one electron to the potassium atom
DNo electrons are transferred or shared
(b)
After the reaction, what charge does the potassium ion carry, and why?
[1 mark]
A1- because it has gained an electron
B1+ because it has lost an electron
C2+ because it has lost two electrons
D0 because it remains neutral
(c)
The company finds that solid potassium chloride does not conduct electricity, but molten or dissolved potassium chloride does. Explain this difference in terms of the ions present.
[2 marks]
Total for question 1: 4 marks
2
An HVAC engineer is choosing a refrigerant gas made of small covalent molecules for a new air conditioning system. The refrigerant must have a very low boiling point so that it evaporates easily inside the system's pipework.
(a)
The refrigerant molecules are held together within each molecule by covalent bonds. What is a covalent bond?
[1 mark]
AA bond formed when electrons are transferred from one atom to another
BA bond formed by delocalised electrons moving freely between many atoms
CA bond formed when a pair of electrons is shared between two atoms
DA bond formed only between two metal atoms
(b)
The engineer needs the refrigerant to have a low boiling point. Why do substances made of small covalent molecules typically have low melting and boiling points?
[1 mark]
ABecause the covalent bonds within each molecule are very weak
BBecause the molecules contain no electrons
CBecause the molecules are giant structures held together by covalent bonds
DBecause only weak intermolecular forces between molecules need to be overcome, not the strong covalent bonds
(c)
The engineer compares two possible refrigerants: one with smaller molecules and one with larger molecules, both made of covalently bonded atoms. Predict, with a reason, which refrigerant would have the higher boiling point.
[2 marks]
Total for question 2: 4 marks
3
A materials laboratory grows synthetic diamond to make ultra-sharp blades for precision surgical scalpels, and separately produces sheets of graphene to reinforce a new lightweight bicycle frame composite.
(a)
Explain, in terms of structure and bonding, why diamond is hard enough to be shaped into a scalpel blade that stays sharp.
[3 marks]
(b)
Graphene is described as a single layer of graphite. Explain how the structure and bonding of graphene make it useful for reinforcing the bicycle frame composite, and why a whole block of graphite would not be as effective for this purpose.
[4 marks]
Total for question 3: 7 marks
4
A materials science lecturer is comparing two very different modern materials for a public talk: brass, an alloy used in musical instrument manufacture, and a nanoparticle titanium dioxide coating used on self-cleaning glass, to show how atomic-scale structure explains very different everyday properties.
(a)
Trumpet manufacturers use brass, an alloy of copper and zinc, instead of pure copper for instrument bodies. Explain, in terms of metallic bonding and structure, why pure copper is too soft for this purpose and why brass is harder.
[6 marks]
(b)
The lecturer also compares nanoparticle titanium dioxide, used in the self-cleaning glass coating, with ordinary bulk titanium dioxide powder. Explain why the nanoparticle form behaves differently from the bulk material, and evaluate one possible risk of using nanoparticles in a coating applied to buildings.
[6 marks]
Total for question 4: 12 marks
5
A forensic science team develops fingerprints on a paper document by placing it in a sealed chamber with a small dish of solid iodine crystals, which are gently warmed so they turn directly into a purple vapour that settles on the invisible fingerprint ridges, without the iodine ever appearing to melt into a liquid.
(a)
The solid iodine turns directly into a vapour without becoming a liquid first. What is this change of state called?
[1 mark]
ASublimation
BEvaporation
CCondensation
DFreezing
(b)
In terms of particle theory, what happens to the iodine particles as the solid changes directly into a vapour?
[1 mark]
AThe particles are destroyed and new particles are created
BThe particles gain energy and overcome the forces holding them in a fixed arrangement, spreading out and moving freely
CThe particles lose energy and move closer together
DThe particles change into a completely different substance
(c)
Explain, in terms of energy and forces between particles, why the iodine vapour later settles back onto the fingerprint ridges as tiny solid deposits when it cools slightly on the paper's surface.
[2 marks]
Total for question 5: 4 marks
6
A ceramics manufacturer makes heat-resistant crucibles from magnesium oxide, an ionic compound, chosen because it can withstand extremely high temperatures inside industrial furnaces without melting or breaking down.
(a)
Magnesium oxide is formed from magnesium (Group 2) and oxygen (Group 6). What charges do the magnesium and oxide ions carry?
[1 mark]
AMagnesium 1+, oxide 1-
BMagnesium 1+, oxide 2-
CMagnesium 2+, oxide 2-
DMagnesium 2-, oxide 2+
(b)
Why does magnesium oxide have such a very high melting point, making it suitable for use in a furnace crucible?
[1 mark]
ABecause it is a small molecule held together by weak intermolecular forces
BBecause its delocalised electrons move freely through the structure
CBecause it has only one type of atom
DBecause strong electrostatic forces of attraction between the oppositely charged ions act in all directions throughout the giant ionic lattice
(c)
Explain why a great deal of energy is needed to melt magnesium oxide, in terms of the forces present in its structure.
[2 marks]
Total for question 6: 4 marks
7
An electronics assembly company selects a lead-free solder alloy of tin and copper for joining components on circuit boards, instead of using pure tin, because pure tin deforms too easily during handling and vibration.
(a)
Explain, in terms of structure and bonding, why pure tin can be bent and shaped relatively easily.
[3 marks]
(b)
Explain why adding copper to tin to make the solder alloy makes it harder and less easily deformed than pure tin, and suggest why this property is important for solder joints on a circuit board that may experience vibration in use.
[4 marks]
Total for question 7: 7 marks
8
A tyre manufacturer adds carbon black nanoparticles to rubber to increase the strength and wear resistance of its tyres, and in the same factory uses graphite powder as a dry lubricant coating on machine parts, taking advantage of very different properties of these two forms of carbon.
(a)
Explain, in terms of structure and bonding, why graphite is useful as a dry lubricant and why it also conducts electricity, unlike diamond.
[6 marks]
(b)
Explain why carbon black, made of carbon nanoparticles, is more effective than an equivalent mass of larger carbon particles at strengthening the rubber in tyres, and evaluate one possible risk of factory workers being exposed to carbon nanoparticles during manufacturing.
[6 marks]
Total for question 8: 12 marks

End of questions