Why do metals have high mp/bp?
- giant metallic structure
- a lot of energy required to overcome strong electrostatic forces of attraction between metal cations and sea of delocalised electrons
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Why do metals conduct electricity?
- giant metallic structure
sea of delocalised electrons are free/ mobile to carry charge
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Why are metals malleable/ ductile?
- giant metallic structure
metallic bonding is not disrupted when the cations are displaced due to sea of delocalised electrons
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Why are alloys harder than pure metals?
pure metals | atoms are of same size; orderly arranged; layers of atoms can slide easily when a force is applied.
alloys | atoms added are of different size; disrupts orderly arrangement; layers do not slide easily when a force is applied.
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State the metal reactivity series.
K, Na, Ca, Mg, Al, C, Zn, Fe, Pb, H, Cu, Ag, Au
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State the four ways in which the reactivity series can be used.
(1/2) displacement of metal salts/ oxides: a more reactive metal can displace a less reactive metal from its salt/ oxide. (3) reduction by carbon: oxides of metals below C can be reduced to the metal by heating with C. (4) thermal stability of carbonates: the more reactive the metal, the harder it for the carbonate to decompose by heating).
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State the 3 substances added to the blast furnace and the purpose of each.
(1) haematite (iron ore): contains iron(III) oxide + silicon dioxide impurities. (2) coke (carbon): to produce carbon monoxide for the reduction of iron(III) oxide to iron. (3) limestone: to remove acidic impurities (silicon dioxide).
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Write the equations to represent the reactions that happen in the blast furnace.
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State the conditions for rusting and methods to prevent it.
Conditions: presence of (1) water & (2) oxygen. Prevention: (1) protective layer (paint, grease, metal) (2) sacrificial protection (3) alloying
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