extraction + uses of metals UPDATED

oxidising agent

the substance in an oxidation reaction

that oxidises the metal

and is reduced

what are unreactive metals often found as and why

- often found uncombined

- as they don't tend to form compounds with other elements

how can uncombined metals be extracted

by finding them and digging them up

where are most metals extracted from

ores found in the Earth's crust

what is a metal ore

a compound that contains enough of the metal to make it worthwhile extracting

are there limited amounts of metal ores

yes they are "finite resources"

how does a metal's reactivity affect the effort taken to extract it from it's compound

the more reactive a metal is, the harder it is to extract it from a compound

as very reactive metals form very stable ores

what are the 2 methods of extraction we need to know

- electrolysis

- reduction using carbon

which metals can be extracted by reduction using carbon

metals less reactive than carbon

how is reduction with carbon carried out

- heating the ore with carbon monoxide

- e.g. iron oxide is reduced in a blast furnace to make iron

why does reduction with carbon work

- more reactive elements form compounds more readily

- carbon is more reactive than the other metal, so gains the oxygen from the metal oxide

how do u extract metals more reactive than carbon

electrolysis

what does electrolysis do

uses electricity to separate the metal from the other elements in the compound

what metals can be found as native metals (uncombined elements) (2)

- silver

- gold

what elements are there very little extraction of

metals below hydrogen

do iron, aluminium and copper have the same properties

they have the same basic properties as they are all metals

properties of iron, aluminium + copper

- dense

- lustrous (shiny)

- high mpts

- high tensile strength (strong + hard to break)

- malleable (can be hammered into a diff shape)

- good conductors of electricity + heat energy

mpt of iron

1538

mpt of aluminium

660

mpt of copper

1085

what is almost completely pure iorn called

wrought iron

properties of wrought iron and uses

- malleable

- so used to make gates and railings

what is the main problem with iron

that it corrodes easily (rusts)

properties of aluminium

- does not corrode easily

- low density

why does aluminium not corrode easily

- it reacts very quickly with oxygen in the air to form aluminium oxide

- a protective layer of aluminium oxide sticks firmly to Al below + stops any further reaction taking place

what does the fact that Al does not corrode easily mean it is useful for

products that come into contact with water e.g. drink cans

what does Al's low density mean it is useful for

when the weight of the metal is important e.g. bike frames, aeroplanes

properties of copper (1)

good conductor of heat and electricity

uses of copper

- electrical components and wiring bc it has low resistance so is efficient at transferring electricity

- used in heating systems e.g. underfloor heating, as it allows speedy transfer of heat to the surroundings

what does the regular structure of pure metals mean pure metals are

makes them soft + means that they are often too soft for use in everyday life

what is an alloy

a mixture of a metal + one or more other elements, usually other metals or carbon

why are alloys harder than pure metals

- diff elements have diff sized atoms

- so when another element mixed with a pure metal, the new atoms will distort the layers of metal atoms

- making it more difficult for them to slide over each other

- so alloys are harder than pure metals

what are alloys of iron called

steels

how are steels made

by adding small amounts of carbon and sometimes other metals to iron

3 types of steel we need to know

- low carbon steel (mild)

- high carbon steel

- stainless steel

what % of carbon in low carbon steel

0.1-0.3% carbon

what % of carbon in high carbon steel

0.22 - 2.5% carbon

what is added to stainless steel

- chromium

- and sometimes nickel

property and use of low carbon steel

easily shaped

car bodies

properties and use of high carbon steel

very strong, inflexible, brittle

bridges

properties and use of stainless steel

corrosion resistant and hard

cutlery