Covalent Bonds: Dot & Cross Diagrams (Edexcel IGCSE Science (Double Award)) : Revision Note
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Dot and cross diagrams for covalent compounds
Covalent substances tend to have simple molecular structures, such as Cl2, H2O or CO2
These small molecules are known as simple molecules
Small covalent molecules can be represented by dot and cross diagrams
You need to be able to describe and draw the structures of the molecules below:
Diatomic Molecules

Dot & cross representation of a molecule of hydrogen

Dot & cross representation of a molecule of chlorine

Dot & cross representation of a molecule of oxygen

Dot & cross representation of a molecule of nitrogen

Dot & cross representation of a molecule of hydrogen chloride
Inorganic Molecules

Dot & cross representation of a molecule of water

Dot & cross representation of a molecule of ammonia

Dot & cross representation of a molecule of carbon dioxide
Organic Molecules

Dot & cross representation of a molecule of methane

Dot & cross representation of a molecule of ethane

Dot & cross representation of a molecule of ethene
Examiner Tips and Tricks
Each covalent bond represents one shared pair of electrons.
For example, there are two covalent bonds between the two oxygen atoms in O2 so four electrons are shared.
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