Metals

Properties of Metals

PhysicalChemical
High densityForm basic oxides
Shiny when polishedForm positive ions
Malleable
Ductile
High m.p. And b.p.
Conductor of heat & electricity

Alloys

  • An alloy is two or more metals, or a metal and non-metal which have been made molten and then mixed together

  • Alloys are used because they have improved qualities for a particular job over the pure metals

AlloyMade fromSpecial PropertiesUses
BrassCopper and zincStronger and more resistant to corrosionElectrical fittings, car radiators
BronzeCopper and tinHarder, stronger and sonorousStatues, springs, coins
Stainless steelIron, chromium and nickelDoes not rustKitchen sinks, cutlery, chemical plant

  • Metals are often used as alloys because they have an increased range of uses and mixture of atoms gives an irregular structure which stops layers sliding over each other easily; they are stronger

  • This is what the structure of an alloy (a) looks like, compared to a pure metal (b).

Reactivity Series

K - Potassium

Na - Sodium

Ca – Calcium

Mg – Magnesium

Al – Aluminium

C – Carbon

Zn – Zinc

Fe – Iron

Pb – Lead

H – Hydrogen

Cu – Copper

Ag – Silver

Au – Gold

This places metals in order of their readiness to take part in
chemical reactions

Everything above hydrogen can displace hydrogen from
its acid, and hydrogen cannot reduce their oxides.

Metals above carbon, their oxides cannot be reduced by carbon.

More reactive metals will react with cold water, and less
reactive will react slowly or not react with steam.

Aluminium seems unreactive because it forms an oxide layer
which protects it

Displacement Reactions

  • These are reactions in which metals compete for oxygen or anions

  • The more reactive metal will displace the less reactive metal from oxygen or an anion.

  • If more reactive metal has oxygen or an anion, no reaction occurs

  • The bigger the difference in reactivity between the two metals, the faster the reaction

Thermal Decomposition

GroupMetal CarbonateMetal HydroxideMetal Nitrate
Group I (except lithium)Do not decomposeDo not decomposeMetal nitrite and oxygen
Group II, lithium & transition metalsMetal oxide and carbon dioxideMetal oxide and waterMetal oxide, nitrogen dioxide and oxygen

Extraction of Metals

  • Ores more difficult to ‎decompose from gold to potassium

  • More powerful/expensive method of ‎extraction from gold to potassium

Metal

Extraction Method

K - Potassium

Na - Sodium

Ca – Calcium

Mg – Magnesium

Al – Aluminum

Reduction via electrolysis

Carbon

Zn – Zinc

Fe – Iron

Pb – Lead

Reducing via heating with Carbon or Carbon Monoxide

Hydrogen

Cu – Copper

Ag – Silver

Au – Gold

Occur naturally

Extracting Iron

  • Ore = hematite (Fe~2~O~3~)

  • Uses of slag

    • To make roads

    • To make cement

  • Coke burns with air

    carbon + oxygen → carbon dioxide

  • Carbon dioxide reacts with coke

    carbon dioxide + carbon →

    carbon monoxide

  • Carbon monoxide reduces Iron(III) oxide to iron

    iron(III) oxide + carbon monoxide → iron + carbon dioxide

  • The limestone reacts with impurities to form slag

    calcium carbonate + silicon dioxide → calcium silicate + carbon dioxide

Iron to Steel

  • Molten iron from blast furnace is poured into an oxygen furnace.

  • Calcium oxide is added, and a jet of oxygen is turned on.

  • The calcium oxide neutralizes acidic impurities, forming slag that is skimmed off and oxygen burns the other impurities away.

  • The carbon content is checked continually until it is just right then the oxygen is turned off.

    • Mild Steel (0.25% carbon) -- Used in machinery and car bodies

    • Medium carbon steel (0.5%) -- Used in railway lines

    • High carbon steel (1.5% carbon) -- Used in knives and blades

Extracting Zinc

  • Ore = Zinc Blende = Zinc Sulphide (ZnS)

  • Zinc blende is roasted in air to convert it to zinc oxide

  • Zinc oxide is reduced using coke to zinc and carbon monoxide in the furnace

  • As zinc is volatile, the gaseous metal is distilled leaving less-volatile impurities behind.

  • Zinc is condensed and liquid is run into mould.

Uses of Metal

  • Aluminum

    • Airplane/Cars (Strong/Low density/resistant to corrosion)

    • Cans/Foil (Resistant to corrosion/malleable)

    • Overhead cable (Good conductor of electricity/ductile)

  • Zinc

    • Galvanizes Iron = coats it to stop it rusting

    • Alloys -- brass/bronze

    • Batteries

    • Sacrificial Protection

  • Copper

    • Electrical Wiring (Good conductor of electricity/Ductile)

    • Cooking utensils (Malleable/good conductor of heat)

    • Roofs (hard wearing against weather