Summary AQA GCSE Chemistry Chemical Changes (Topic 4) Revision Notes

Chemical Changes
Reactivity Series:
 The reactivity series lists metals in order of their reactivity towards
other substances.
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
Platinum
Metal Reactions:
 Oxidation reactions – a reaction where a substance gains oxygen
and/or loses electrons
 Reduction reactions – a reaction where a substance loses oxygen
and/or gains electrons
 Metal + Oxygen  Metal Oxide
e.g. sodium + oxygen  sodium oxide
4Na + O₂  2Na₂O
 Metal + Water  Metal Hydroxide + Hydrogen
e.g. potassium + water  potassium hydroxide + hydrogen
2K + 2H₂O  2KOH + H₂
 Metal + Acid  Metal Salt + Hydrogen
e.g. calcium + hydrochloric acid  calcium chloride + hydrogen
Ca + 2HCl  CaCl₂ + H₂
 Displacement reactions – reaction where a more reactive element
takes the palace of a less reactive element in a compound.
e.g. aluminium + iron oxide  aluminium oxide + iron
2Al + Fe₂O₃  Al₂O₃ + 2Fe
 Oxidation is a reaction where a substance loses electrons.
 Reduction is a reaction where a substance gains electrons.
 A redox reaction is a reaction where both reduction and oxidation take
place.