By Miss Buicke Metals and Non-metals. What we need to know from the syllabus : OC45 understand that...

By Miss Buicke

Metals and Non-metals

What we need to know from the syllabus:

OC45 understand that rusting is a chemical process that changes iron

into a new substance

OC46 carry out an experiment to demonstrate that oxygen and water are

necessary for rusting

OC47 list three examples of methods of rust prevention: paint, oil,

galvanising

OC52 investigate the relative reactivities of Ca, Mg, Zn, and Cu based on their

reactions with water and acid (equations not required)

OC10

Understand that metals are shiny (lustrous), can be beaten into

shape (malleable) and can be stretched (ductile)

OC11

Understand that solder, steel, brass and bronze are alloys, and state

one use of each alloy

OC6 recall that metals conduct electricity and heat

OC7 identify everyday applications of metals, for example in industry, in

the making of jewellery

Most of the elements in the periodic table are metals. Only the elements on the right-hand side of the periodic table are non-metals.

Everyday examples of where metals are used:

• Jewellery• Engineering structures, e.g. bridges• Cars • Electrical wires

Physical properties of metals:

1) Metals have high melting points.

2) Metals are shiny but many turn dull due to oxidation in air.

3) Metals conduct heat.

4) Metals conduct electricity, non-metals do not

5) Metals are malleable.They can be hammered into different shapes e.g aluminium can be flattened into very thin sheets and sold as ‘tinfoil’

6) Metals are ductile.They can be stretched out into wire e.g copper.

7) Metals are hard and strong.

Some exceptions:Not all metals have all these properties.• The alkali metals are soft with low densities.• Mercury is a liquid at room temperature.

Non metals (non-metallic elements)Non- metals are situated to the right on the periodic table. They are usually liquids or gases at roomtemperature and are poor conductors of heat and ElectricityExample of non metals:Nitrogen, oxygen, chlorine, bromine and carbon.

Bromine chlorine

The properties of non-metals are usually the opposite to those of metals. But of course there are always exceptions.

• carbon in the form of graphite is a good conductor of electricity.• Carbon in the form of a diamond is extremely

hard with a high melting point.

Alloys:An alloy is a mixture of metals.

alloy composition usebrass Copper and

zincMusical instruments

bronze Copper and tin statuesSolder

steel

Lead and tin

Iron, chromium and nickel

Soldering

Sinks and knives

Corrosion of metalsMost metals are reactive. They react with air and water and as a result corrode. When a piece of sodium is cut, a shiny surface can be seen. This will quickly lose its shine as it reacts with oxygen.

Metals such as gold and silver are very unreactive and are use in the manufacture of jewellery.

RustingThe corrosion of iron is called rusting

Iron reacts with both water and oxygen and forms iron oxide or rust.

Rust prevention:Rusting of iron or steel costs us millions of euros each year. Any object containing iron will rust if exposed to water and oxygen.

Rusting can be prevented by coating the metal with a material to prevent water and oxygen Coming into contact with it.

painting

Galvanising ( coating with

zinc)

Tin plating ( coat with tin)

Greasing (coat of oil or grease)

Plastic coating

Rust prevention:

Mandatory experiment:To carry out an experiment to demonstrate that oxygen and water are necessary for rusting.

Apparatus: test tubes, steel nails, stoppers, test tube rack.

chemicals: oil, water, calcium chloride (drying agent)

Method: 1. Set up three test tubes.Test tube one: calcium chloride and nailTest tube two: boiled water, layer of oil and nailTest tube three: unboiled water and nail.

2. Examine the test tubes after one week.

Result: the nail in test tube three will rust as it is exposed to both water and oxygen.

Conclusion: In order for rusting to occur both water and oxygen must be present.

The activity seriesThe order in which metals react with water and acid is called the activity series.

orThe activity series is a list of metals placed in order of how reactive they are (Ca, Mg, Zn, Cu)

To investigate the relative reactivities of Ca, Mg, Zn, and Cu based on their reactions with water and acid.

Procedure:1. Add water to 4 test-tubes and place them in a test-tube rack.2. Carefully drop one of the metals in to each test-tube and observe the reaction in each.Result:The most vigorous reaction was in the test-tube containing calcium, then magnesium, zinc and finally copper (which didn’t react at all).

To investigate the relative reactivity of Ca, Mg, Zn, and Cu based on their reactions with acidProcedure:1. Add dilute acid to 4 test-tubes and place them in a test-tube rack.2. Carefully drop one of the metals in to each test-tube and observe the reaction in each.Result:The most vigorous reaction was in the test-tube containing calcium, then magnesium, zinc and finally copper.Conclusion:Metals react more strongly with acid than with water

Reactivity of metals:Some metals are more reactive then others.

We must know the following order of reactivity:

calcium magnesium zinc copper

Calcium is the most reactive and copper is the least reactive.