Topic 4: Chemical Changes

Metal oxides metals + oxygen → metal oxides oxidation reactions = the gain of oxygen by a substance during chemical reactions reduction = loss of oxygen magnesium + oxygen → magnesium oxide 2Mg(s) + O₂(g) → 2MgO(s) Copper oxide + carbon → copper + carbon dioxide 2CuO(s) + C(s) → 2Cu(l) + CO₂(g)    -   carbon is oxidised because it gains oxygen    -   copper oxide is reduced because oxygen is removed from it

The reactivity series    -   when metals react with other substances, metal atoms form positive ions    -    reactivity of a metal is related to its tend ency to form positive ions A more reactive metal can displace a less reactive metals from a compound