Practise bonding classification, alloy structure and polymer chemistry to explain how composition and molecular architecture shape material properties and uses.
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.
Explain why the addition of small amounts of carbon to iron makes the metal harder.
disrupts the regular arrangement «of iron atoms/ions»
OR
carbon different size «to iron atoms/ions»
prevents layers/atoms sliding over each other
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
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.