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Covalent bonding

Dot-and-cross diagrams - elements

Dot-and-cross diagrams

Dot-and-cross diagrams are used to represent covalent bonds. The shared electron from one atom is shown as a dot, while the shared electron from the other atom is shown as a cross.

When drawing dot-and-cross diagrams for covalent bonds, you only need to show the electrons in the highest occupied energy level, as only these are involved.

The animations show covalent bonds represented by both displayed formulae (which use straight lines to represent bonds) and dot-and-cross diagrams:

Covalent bonding between two hydrogen atoms to form a molecule of hydrogen gas, H2.

Covalent bonding between two oxygen atoms to form a molecule of oxygen gas, O2.


For your examination, you need to be able to draw dot-and-cross diagrams for hydrogen, chlorine and oxygen.

Bonding in hydrogen: two hydrogen atoms each share one electron

Bonding in chlorine. Two chlorine atoms each share one electron

Bonding in oxygen. Two oxygen atoms each share two electrons

You do not need to use colours in your answers.

Back to Structure and bonding index

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