Chemical changes

Metal oxides

• metals react with oxygen to produce metal oxides

• Oxidation reactions because the metals gain oxygen

The reactivity series

• potassium

• Sodium

• Lithium

• Calcium

• Magnesium

• Carbon

• Zinc

• Iron

• Hydrogen

• Copper

• Gold

what happens when metals react with other substances

the metal atoms form positive ions

What does the reactivity of the metal related to

• the tendency to form positive ions

• The more that a metal can form positive ions, the more reactive it is

Metals reacting with water

• metal + water → metal hydroxide + hydrogen

• Some metals form positive ions when they react with water, so the reaction can be used to compare their reactivity

which metals will react with water

• the more reactive metals e.g. group 1 metals potassium, sodium and lithium as well as the group 2 metal calcium

• Metals that aren’t very reactive e.g. zinc, iron and copper won’t react with water

potassium and water

• potassium + water → potassium hydroxide + hydrogen

• 2K + 2H₂O → 2KOH + H₂

Calcium and water

• calcium + water → calcium hydroxide + hydrogen

• Ca + 2H₂O → Ca(OH)₂ + H₂

metals with acids

Metal + acid → salt + hydrogen

How to tell reactivity of metal based on reaction with acid

• monitoring the rate of hydrogen production when they react with acid

• Production of hydrogen detected by the burning splint test

• More reactive = faster reaction

• Speed is indicated by rate at which hydrogen bubbles are given off

How do different metals react with acids

• very reactive (K, Na, Li, Ca) → react explosively

• Less reactive (Mg, Zn, Fe) → react less violently

• copper won’t react with cold, dilute acids

Displacement reactions

• a more reactive metal can displace a less reactive metal from the compound

• e.g. iron + copper (II) sulfate → iron (II) sulfate + copper

• Fe + CuSO₄ → FeSO₄ + Cu

which metals are found in the earth as the metal itself

unreactive metals such as gold

How are metals less reactive than carbon extracted from their oxides

• by reduction with carbon

• Reduction involves the loss of oxygen

Oxidation

loss of electrons

Reduction

gain of electrons

what happens when an acid reacts with an alkali

• neutralisation reaction

• Acid + alkali → salt + water

Soluble metal hydroxides + acid