Covalent Bonds: Dot & Cross Diagrams (Edexcel IGCSE Science (Double Award) (Modular)): Revision Note

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