Download Unit 3 National 4 Summary Sheet Key Area: Metals and alloys What

Unit 3 National 4 Summary Sheet
Key Area: Metals and alloys
What I should know or be able to do
 

All metal have common properties e.g. they conduct electricity
and heat.
The chemical and physical properties of materials are linked to
their uses.
Metals react with oxygen to form metal oxides e.g. copper
oxide.
Some metals react with water. Hydrogen gas is produced.
Some metals react with dilute acid. Hydrogen gas is produced.
Hydrogen gas burns with a pop.
A reactivity list can be made by looking at these reactions.
Some metals can be found uncombined in the earth’s crust.
They are unreactive e.g. gold, platinum.
Other metals are found combined with other elements in ores.
Methods used to extract metals from their ores depend on the
position of the metal in the reactivity series e.g.
 Silver: heat alone from silver oxide
 Copper: from copper oxide using carbon
 Aluminium: from molten aluminium oxide by electrolysis
Both oxygen and water are needed for metals to corrode
Some metals corrode faster than others.
The corrosion of iron is called rusting.
Ferroxyl indicator can be used to show rusting occurring. It
turns blue.
Some conditions speed up rusting e.g. the presence of acid and
salt
Iron can be protected from rusting using different methods.
 Sacrificial protection - attaching a more reactive metal
to the iron.
 Galvanising : iron is coated with zinc
 Painting or greasing
 Alloying(see below) e.g. stainless steel
An electrolyte is a solution containing ions.
When two metals are connected by an electrolyte, an electric
current flows from the more reactive metal to the other
through the wires.
1
By comparing pairs of metals the electrochemical series can be
constructed.
The electrochemical series is used to predict the size of voltage
and direction of current in chemical cells. This forms the basis
for batteries.
An alloy is a mixture of two or more elements, at least one of
which is a metal.
Alloys have different physical properties to the elements from
which they are made.
I can name at least one alloy and describe its properties and
uses.
Key Area: Materials
What I should know or be able to do
 

Plastics are long-chain molecules called polymers.
They are made by a reaction called polymerisation.
Polymerisation involves an addition reaction where small units
called monomers join together.
Given the name of the monomer I can name the polymer formed
e.g. ethene  poly(ethene);
tetrafluoroethene
 poly(tetrafluorethene)
Plastics release harmful gases when they burn.
Polymers can be developed for use in different environments
e.g. biodegradable plastic for food recycling bags.
Thermoplastics can be reshaped after heating.
Thermosetting plastics cannot be reshaped after heating.
I can describe the properties of ceramics including strength
and heat resistance
New materials are always being developed to meet the demands
of society.
Describe the properties of some novel materials. eg:
conductivity, solubility, colour changing, water absorption.
Key Area: Fertilisers
There are three key elements which provide the nutrients
required for plant growth: nitrogen, phosphorus and potassium
I can calculate the % composition of an element in a fertiliser.
% = mass of element in fertiliser formula X 100
Formula mass of fertiliser
2
Fertilisers can be produced naturally or in laboratories by
chemists using neutralisation reactions.
I can choose appropriate reactants to make a named fertiliser.
Fertilisers must be soluble in water to be effective.
I can describe the environmental impact of fertilisers.
Key Area: Nuclear chemistry
I know how background radiation is measured using a GeigerMuller tube.
I know some sources of background radiation e.g. cosmic rays,
rocks and soil, living things, medical x-rays, radioactive waste.
Chemical analysis
I can carry out the following techniques
 paper chromatography
 flame tests
 pH measurement using indicators
 separation techniques
3