Oxidation is the loss of electrons by a substance in a chemical reaction. Reduction is the gaining of electrons by a substance. This can be remembered with the acronym OILRIG ; Oxidation Is Losing Reduction Is Gaining. The substance which accepts the electrons is the oxidising agent, and the substance which gives the electrons is the reducing agent.

In an ionic reaction, the metals are oxidised, they have lost electrons, and the non metals are reduced, they have gained electrons. The metals are the reducing agents and the non metals are the oxidising agents.

Ionic equations show the oxidised and reduced ions in a chemical reaction. For example, zinc metal can displace copper ions from a solution of copper(II) sulphate. Copper metal and zinc(II) sulphate solution are formed. As a normal (unbalanced) equation, it would be set out as... Zn + CuSO4 ---> Cu + ZnSO4. As an ionic equation, it would be set out like... Zn + Cu^(2+) + SO4^(2-) ---> Cu + Zn^(2+) + SO4^(2-) . The molecules are "separated" and their individual charges are shown before and after the reaction.

Before, zinc is a metal so it has no charge, copper has a 2+ charge because it is bonded with sulphate, which has a 2- charge, an since there is only 1 copper the charges must balance out, (also it says copper(II) in the question).

After, copper is a metal so it has no charge, zinc has a 2+ because it is bonded with sulphate (full reason above), (also it says zinc(II) is formed in the question).

Zinc is shown to have become +ve i.e. it has lost electrons so it has been oxidised. The copper has become neutral form +ve, i.e. it has gained electrons,so it has been reduced. The sulphate ions have not changed in charge, so they are spectator ions.

	Created by Fatima Hussain about 6 years ago

Year 10 Chemistry Slide Set on Atomic Bonding, created by Fatima Hussain on 02/04/2018.