IB Chemistry SL From Models to Materials
Review IB Chemistry from models to materials through bonding-triangle predictions, alloy structures, polymer classes and structure-property links.
- Syllabus
- First assessment 2025
- Topic
- 2.4
- Level
- SL
Exam points
- use electronegativity data and the bonding triangle to predict bonding and properties
- explain alloy properties from disrupted metal layers and non-directional metallic bonding
Covered syllabus points
2.4 From models to materials question 1
[Maximum number: 1]
Iron may be extracted from iron (II) sulfide, FeS.
Iron (II) sulfide, FeS , is ionically bonded.
Suggest why chemists find it convenient to classify bonding into ionic, covalent and metallic.
allows them to explain the properties of different compounds/substances OR enables them to generalise about substances
OR enables them to make predictions
Marking guidance:
Accept other valid answers.
2.4 From models to materials question 2
[Maximum number: 1]
Iron(II) sulfide can be produced by heating powdered iron and sulfur together.
Outline why solid iron(II) sulfide is a polar covalent compound. Use sections 9 and 17 of the data booklet.
<<electronegativity difference>> ΔX=0.8 AND average
<<electronegativity >> X = 2.2
2.4 From models to materials question 3
[Maximum number: 2]
Titanium is a transition metal.
Explain why an aluminium-titanium alloy is harder than pure aluminium.
titanium atoms/ions distort the regular arrangement of atoms/ions OR titanium atoms/ions are a different size to aluminium «atoms/ions» prevent layers sliding over each other
Marking guidance:
Accept diagram showing different sizes of atoms/ions.
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