Alloys (Edexcel GCSE Chemistry)
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Alloys
Alloys are mixtures of metals, where the metals are mixed together physically but are not chemically combined
They can also be made from metals mixed with nonmetals such as carbon
Alloys often have properties that can be very different to the metals they contain, for example they can have greater strength, hardness or resistance to corrosion or extreme temperatures
Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms
This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal
Brass is a common example of an alloy which contains 70% copper and 30% zinc
Particle diagram showing a mixture of elements in an alloy. The different sizes of the two types of atoms prevent the layers of atoms from sliding over each other, so the alloy becomes less malleable than the pure metal
Examiner Tips and Tricks
Questions on this topic often give you a selection of particle diagrams and ask you to choose the one which represents an alloy. It will be the diagram with uneven sized particles and distorted layers or rows of particles.
Steel Alloys
Steel Alloys
Iron from a blast furnace is an alloy of 96% iron, with carbon, phosphorus, silicon and sulfur impurities
It is called cast iron and is too brittle for many uses, so most of it is converted into steel by removing some of the impurities
Not all of the carbon is removed as steel contains some carbon, the percentage of which depends on the use of the steel
Alloys of steel are made from adding other metals to steel such as chromium, manganese or nickel
By carefully controlling the amounts added, the particular type of alloy required can be produced
Steel alloys are used in construction, transport, manufacturing and other industries
Steel Alloys & their Uses
Examiner Tips and Tricks
Alloys are mixtures of substances, they are not chemically combined and an alloy is not a compound.
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