Loss & Gain of Electrons (GCSE Chemistry)
Loss & Gain of Electrons
Oxidation and Reduction
Electron Transfer
- A redox reaction involves the transfer of electrons. During a redox reaction, there is a gain of electrons in one molecule and loss of electrons in another.
- Oxidation is the loss of electrons. We can look at oxidation in terms of what happens to the electrons. Oxidation is the loss of electrons and the gain of oxygen.
- Reduction is the gain of electrons. We can also look at reduction in terms of what happens to the electrons. Reduction is the gain of electrons and the loss of oxygen.
Displacement Reactions
- Displacement reactions are redox reactions. We’ve just learnt that redox reactions have reduction and oxidation occurring at the same time. The metal ion is reduced (gains electrons) and the metal atom is oxidised (loses electrons).
- Displacement uses metal reactivity. Displacement reactions occur when a more reactive metal switches places with (or displaces) the less reactive metal within a compound.
Practice Question: Show which substances are oxidised and reduced in the reaction between magnesium and zinc chloride.
Magnesium + zinc chloride → magnesium chloride + zinc
1. Write the symbol equation.
Mg + ZnCl2 → MgCl2 + Zn
2. Write out the all the ions involved.
Mg + Zn2+ 2Cl– → Mg2+ 2Cl– + Zn
3. Identify the spectator ions. We need to remove the spectator ions, which are the ions which are unchanged during the reaction.
Mg + Zn2+ 2Cl– → Mg2+ 2Cl– + Zn
4. Cancel out the chlorines. These have remained unchanged on either side of the reaction.
Mg + Zn2+ → Mg2+ + Zn
5. Write the half equations. This shows which is oxidised and which is reduced during the displacement reaction.
Mg – 2e– → Mg2+ Magnesium loses 2 electrons, so it is oxidised
Zn2+ + 2e– → Zn Zinc gains 2 electrons so it is reduced
The loss and gain of electrons, also known as oxidation and reduction, are important chemical reactions in GCSE Chemistry. In oxidation, an atom or molecule loses electrons, while in reduction, an atom or molecule gains electrons.
Many real-life examples of loss and gain of electrons can be found in everyday life. For example, when iron rusts, it undergoes oxidation as it loses electrons. When a battery powers a device, it is undergoing reduction as it gains electrons.
The loss and gain of electrons are important in chemistry because they are involved in many chemical reactions. These reactions can be used to generate energy, produce useful products, and even power electronic devices.
One way to tell if a substance has undergone oxidation or reduction is to look at the oxidation numbers of the atoms in the substance. If the oxidation number has increased, the substance has undergone oxidation, and if it has decreased, the substance has undergone reduction.
The loss and gain of electrons are the basis of redox reactions, which involve both oxidation and reduction. In a redox reaction, one substance is oxidized while another is reduced, and the electrons that are lost by one substance are gained by the other.
The loss and gain of electrons play a major role in determining the reactivity of elements. Elements that are more likely to lose electrons, such as metals, are more reactive, while elements that are more likely to gain electrons, such as nonmetals, are less reactive.
Combustion is a type of oxidation reaction that occurs when a substance reacts with oxygen to produce heat and light. The fuel undergoes oxidation as it loses electrons to the oxygen, and the oxygen undergoes reduction as it gains electrons from the fuel.
The main difference between oxidation and reduction is that in oxidation, an atom or molecule loses electrons, while in reduction, an atom or molecule gains electrons. Oxidation and reduction always occur together in a redox reaction.
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