Properties of Metals & Alloys

Which statement about alloys is correct?

• They are good conductors of electricity as they have mobile ions.

• The are formed by a chemical reaction between two metals.

• They can all be represented by a molecular formula.

• Their structures contain a 'sea of delocalised valence electrons'

Answer explanation

An alloy is a mixture of metal an other metals or non-metals.

Mixtures usually have similar properties to its constituent substances. For alloys, they will have similar properties to metals - electrical conductivity.

The ability for metals & alloys to conduct electricity is the presence of a 'sea of mobile delocalised valence electrons'.

Duralumin is an aluminium alloy that contains copper.

Which statement about duralumin is correct?

• It contains aluminium and copper that are chemically combined.

• It contains mobile electrons.

• It has a lattice of oppositely-charge aluminium ions and copper ions.

• It has the same melting point as copper.

Which property is true for ALL metals?

• good conductors of heat and electricity

• high melting points

• high densities

• soft and easily cut with a knife

Explain why alloys are stronger and harder than pure metals.

Brass is an alloy of copper and (a)   .

Steel is an alloy of (a)   and carbon.

Bronze is an alloy of copper and (a)   .