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8G (8Ge (Metals and alloys) (Mixture of metals (e.g. bronze, brass,…
8G
8Ge (Metals and alloys)
Mixture of metals
e.g. bronze, brass, stainless steel, duralumin
Atom arrangement
Pure metal:
in even layers
Alloys: layers
distorted by different size of atoms
Force effect:
Pure metal: moves layers
over each other
Alloys: can't (stopped by different sizes of atoms)
Movement of layers
Pure metals:
slide over easily
Alloys: can't
Melting points
Pure metals: precise, higher
Alloys:
larger range, lower
(by impurities)
Different propertes
Different uses
8Gb (Describing Materials)
appearance
attractive, dull, fresh, glossy, grey, lustrous,
new, metallic, round nice-looking, polished,
pretty, shiny, silver, soft, small, solid, squashy
chemical properties
flammable, reactive
hardness/ flexibility
bendy, firm, weak, flexible, malleable, ductile
density
light, low-density
conductivity
electrical/ heat-conducting
8Ga (Metal properties)
Chemical properties
(physical one in 8f)
Reactions with other substances
With other non-metals, air (oxygen), water and acids
React quickly:
Reactive
(e.g. calcium)
Unreactive: e.g. gold
Uses of metals
Depends on their different
properties
e.g. copper for electrical wires:
ductile, good conductor of electricity
Metal catalysts
Speed up
chemical reactions
without being used up
e.g. platinum used in catalytic converters in cars
8Gc (Metals and Water)
All metals that react with water form a
metal
hydroxide
(alkaline) and
hydrogen
gas
Test for hydrogen gas:
Place a burning splint near hydrogen
and it burns with a 'pop' sound.
Metal + water --> Metal hydroxide + hydrogen
Reactions of metals with oxygen, water and acids let us put them in
order of reactivity
(reactivity series: P.109)
8Gb (Corrosion)
Any reaction with oxygen at the surface of a metal
Rusting: specifically for
corrosion of iron
Both water and oxygen
must be present
Coating with
painting, powder, plastic
act as a
barrier
to stop oxygen and water
Sacrificial protection: put
more reactive
metals on surface
Alloys of iron:
stainless steel
to fight against corrosion
8Gd (Metals and Acids)
Metal + acid --> Salt + hydrogen
Hydrochloric acid:
chlorides
Sulphuric acid:
sulphate
Nitric acid:
nitrate
Reactivity series (P.112)
8Gd (Quality Evidence)
Accuracy:
How close a measurement is to its real value
Reliability:
Results all very close together:
repeatable
Other people can get similar values:
reproducible