Chemistry- Metals

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The History of Metals
* Uses of metals through history:
* Copper Age (3200-2300 BCE) – copper and tin were most common metals, and were used for ornaments, weapons and tools. * Bronze Age (2300-700 BCE) – copper, tin and bronze were used for tools, weapons and transport. They produced bronze by heating copper and tin with charcoal. * Iron Age (1000 BCE – 1 CE) – iron steel and lead was used for tools, weapons and pipes. Iron is much harder than bronze. * Modern Age (1 CE – Present) – main metals are iron, aluminium and steel, which were used for pipes, buildings, transport and electrical cables. This is the age where technology of iron and steel improved. Around the 1880’s, there was a significant move towards new alloys and metals, including tungsten steel (cutting tools), manganese steels (railway lines and digging tools), silicon, chromium, nickel and vanadium. * Uses of metals

* Iron and steel – railways, bridges, roofing, motor car bodies, ships, fire hydrants, domestic appliances, heavy industrial machinery, pipes, nails. * Aluminium – buildings, aeroplanes, car parts, domestic pots and pans, wrapping foil. * Copper – electrical wiring, pipes and plumbing fittings, jewellery. * Zinc – protective paints, galvanizing irons

* Lead – car batteries, plumbing, solder.
* An alloy is a homogeneous mixture of a metal with one or more other elements Alloy| Properties| Uses|
Stainless Steel (10-20% chromium, 5-20% nickel, iron)| * Hard * Resists corrosion| food processing machinery, kitchen sinks and appliances, cutlery, surgical and dental instruments, razor blades| Brass(50-60% copper with zinc)| * Lustrous gold appearance * Hard * Easily machined| Plumbing fittings, musical instruments, decorations| Bronze(80-90% copper and tin)| * Hard * Resists corrosion * Easily cast| Ships propellers, casting statues| Duralumin(95% aluminium, 4% copper and 1% manganese)| * Low density * Very strong| Aircraft parts, racing bicycles| Solder(30-60% tin with lead)| * Low melting point * Adheres firmly to other metals when molten| Joining metals together, especially in plumbing and electronics| * A large amount of energy input is necessary for the extraction of metals from their ores, because energy is required to: * Mine the ore

* Purify or concentrate the ore
* Maintain the high temperatures needed to make the extraction reactions * Purify the raw metal or to form it into useful alloys Reactions of Metals
* Reaction with oxygen (oxidation, corrosion)
* All metals except silver, platinum and gold form oxides * It is the least and slowest reaction, and only occurs with the strong reactive metals * Most obvious observation is rust or loss of the shiny lustrous appearance * 2Mg(s) + O2(g) →2MgO(s)

* 4Fe(s) + O2(g) → 2Fe2O3(g)
* Reaction with acid
* All metals except copper, silver, gold and platinum react with acid to form hydrogen gas * It is the fastest and most obvious reaction, occurring with most metals * Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

* 2Fe(s) + 6HNO3(aq) → 2Fe(NO3)2(aq) + 3H2(g)
* Reaction with water
* If water, forms metal hydroxide and hydrogen gas
* If steam, forms metal oxide and hydrogen gas
* 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
* Ca(s) + H2O(g) → CaO(aq) + H2(g)
* Based on how reactive metals are with these substances allows us to conclude an activity series of most to least reactive metals. * K Na Li Ba Ca Mg Al Zn Fe Sn Pb Cu Ag Pt Au
* The reaction of metals with acids requires the transfer of electrons. * For the reaction of aluminium with dilute acid, the half reactions are: * Al → Al3+ + 3e-
* 2H+ + 2e- → H2
* To balance these equations, there must be equal amount of electrons in both equations....
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