Practise bonding classification, alloy structure and polymer chemistry, including how monomers, chain architecture and condensation shape material properties.
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
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
A sample of bromine has the following composition by mass:
Deduce, showing your working, the type of bonding and percentage covalent character in calcium bromide, CaBr2. Use sections 9 and 17 of the data booklet.
«electronegativity difference => 2.0 AND «average electronegativity => 2.0
ionic AND 35% covalent
Marking guidance:
Accept range 30-40% for percentage
covalent character.
Titanium and vanadium are consecutive elements in the first transition metal series.
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
Accept diagram showing different sizes of atoms/ions.