extraction and uses of metals

how are most metals obtained

extracted from ores found in the earth’s crust

what about unreactive metals

often found as the uncombined element

ore definition

naturally occurring rocks that contain metal/metal compounds in sufficient quantities to extract

how to extract metal with carbon [4]

heat metal compound with carbon

carbon displaces metal in compound

metal is left as uncombined element

often done at high temps e.g. blast furnace

criteria for carbon extraction for metals [3]

must be less reactive than carbon

so it can be displaced

e.g. iron

how to extract metal with electrolysis [3]

melt metal compound

run current with anode and cathode

metal will form around cathode

criteria for electrolysis extraction [3]

none - all metals can be used (incl. ones also eligible for carbon extraction)

however v. expensive

b/c lot of energy needed to melt metal compound & produce current

properties of aluminium

low-density & corrosion-resistant

uses of aluminium

aircraft, overhead power cables, cooking foil

properties of copper

soft & easily bent, good conductor of electricity, doesn’t react with water, antibacterial properties

uses of copper

electrical wiring, plumbing, hospital surfaces

properties of iron

if from blast furnace - hard but too brittle for most uses

if pure - too soft for most uses

so converted to steel

properties of low carbon (mild) steel

0.25% carbon, easily shaped

use of mild steel

car body panels

properties of high carbon steel

2.5% carbon, hard

use of high carbon steel

cutting tools

properties of stainless steel

contains chromium & nickel, corrosion-resistant (doesn’t rust)

uses of stainless steel

cutlery and sinks

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 [8]

in a pure metal, ions are all the same size

and in a regular arrangement of layers

so can slide over each other easily

so are soft

in alloy, different sized ions

disrupts regular arrangements

makes it harder for layers to slide over each other

so are harder