Spur your students on with this step-by-step approach to covalent bonding

Cartoon molecule models and electron shell diagrams

Source: © Dan Bright

Once they have mastered electron configuration diagrams, show your learners how they can adapt them to show structure and bonding in covalent and ionic compounds. These structural diagrams depict only the outer, or valence, shell electrons and are known as dot and cross diagrams. Electrons from different atoms use alternating symbols, usually a dot and a cross, to show which atom the electrons have come from.

Let’s take a closer look at some compounds containing nitrogen. Remember that nitrogen has five electrons in its outer shell.

How to draw a dot and cross diagram for ammonia

In NH3, commonly known as ammonia, nitrogen forms three single covalent bonds with three hydrogen atoms.

This method is easiest for single covalent bonds as there is not much room where the atoms’ shells touch for drawing lots of electron pairs.

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Infographic poster, fact sheet, worksheet and teacher notes. Display the poster in your classroom or on a projector. Alternatively, print it and use it as a handout.

Use the accompanying fact sheet and worksheet to get your students practising dot and cross diagrams. Go to the accompanying resource for further information about how to use the Covalent bonding tiles.

  • Poster as pdf
  • Fact sheet as MS Word or pdf
  • Covalent bonding tiles student worksheet as MS Word or pdf
  • Covalent bonding tiles teacher notes and answers as MS Word or pdf

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How to draw double and triple bonds

This first method (blue background) is useful for double and triple bonds as it gives more space for drawing electrons. This second method (pink background) is useful for checking that you have drawn the right number of electrons in the outer shell of each atom.

More resources

  • Spot misconceptions that learners may have when identifying the type of bonding in various chemical compounds with this student worksheet.
  • Ensure that students have a strong foundation in drawing electron configuration diagrams with this infographic, fact sheet and worksheet.
  • Use this activity to help learners develop an understanding of covalent bonding in terms of energetic stability rather than full shells.
  • Inspire students to share their passion for chemistry by becoming a science communicator or teacher.

All illustrations © Dan Bright 

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