presentation kimia (2)
TRANSCRIPT
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From: 4 Sumaiyah and
4 Siti Aisyah
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The physical properties ofThe physical properties ofpure metalpure metal
properties reasons
high melting and boilingpoint
Strong force ofattraction between the
negative charge andpositive charge
Good conductor of heatand electricity (in solid
and molten state
Presence of free electroncarried heat and
electricity energy
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Malleable and ductile Layer of metal atomcan slide over each
other withoutdisrupting of metallic
bonding. Hence metallicbonds are strong and
flexible
Have high density In solid state the atomin a pure metal are
orderly arranged andclosely packed causespure metal to have high
density
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Metal are ductileMetal are ductile
The orderly arrangement of atom in metal enable theThe orderly arrangement of atom in metal enable thelayer of atom to slide on one another when force islayer of atom to slide on one another when force isapplied as show in figure :applied as show in figure :
Force applied
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Metal are malleableMetal are malleable
There are some imperfections in the orderlyThere are some imperfections in the orderlyarrangement of atom in metal that allow some emptyarrangement of atom in metal that allow some emptyspace in between the atom. When metal is knock ,atomspace in between the atom. When metal is knock ,atomslide. This is why metal are malleable.slide. This is why metal are malleable.
Force
applied
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WHAT ARE ALLOYS?WHAT ARE ALLOYS? Pure metal are usually too soft for most uses. They
also have a low resistance to corrosion. They rushand tarnish easily.
To improve the physical properties of metal, a small
amount of another element (usually metal) is addedto form another an alloy.
An alloy is a mixture of two or more metals(something non-metal) in a specific proportion. For
example: Bronze (90% of copper and 10% of tin) Steel (99% of iron and 1% of carbon)
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The purposes of making alloysThe purposes of making alloysinclude the following:include the following:
Increase the strength
Pure iron is soft and vary malleable. When asmall amount of carbon is added to iron, an alloy,
steal is formed. The more carbon is added, thestronger the steel becomes.
Pure aluminium is light but not strong. With asmall amount of copper and magnesium areadded to aluminium, a strong, light and durablealloy call duralumin is produced.
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Purpose making alloyPurpose making alloy
Improving the resistance tocorrosion
Iron rust easily but stainless steel whichcontains 80.6% of iron, 0.4% of carbon, 18% of
chromium and 1% of nickel does not rush. Theseproperties make stainless steel suitable formaking surgical instrument and cutlery.
Pure copper tarnish easily. When zinc (30%) is
added, the yellow alloy which is known as brassdevelops a high resistance to corrosion.
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Purpose making alloyPurpose making alloy
-Enhancing the appearance
Pewter, an alloy of tin (97%), antimony and copper isnot only hard but also has a more beautiful whitesilvery appearance.
When copper is mixed with nickel to form cupronickel,an alloy that has an attractive silvery, brightappearance is formed which is suitable for makingcoins.
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Composition , properties and usesComposition , properties and usesof alloyof alloy
Alloy Composition Properties Uses
Bronze *90% copper
*10% tin
*hard andstrong
*does notcorrode easily
*has shinysurface
*in the buildingof statues ormonuments
*in the makingof medals,sword andartistic material
Brass *70% copper*30% zinc
*harder thancopper
*in the makingof musicalinstrument andkitchenware
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Steel *99% iron
*1%carbon
*hard and strong *in theconstruction ofbuilding and
bridge*in the buildingof body of carand railwaytrack
Stainless steel *74% iron*8%carbon
*18% chromium
*shiny*strong
*does not rust
*in the makingcultery
*in the makingsurgicalinstrument
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Duralunium *93% aluminium
*3% copper
*3% magnesium*1% manganese
*light
*strong
In the building ofthe body of
aeroplane andbullet trains
Pewter *96% tin
*3% copper
*1% antimony
*lustre
*shiny
*strong
In the making ofsouvenirs
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Arrangement of atom in alloyArrangement of atom in alloy