Improve your post-16 learners’ understanding of electronegativity and intermolecular forces

Pure covalent bonding and ionic bonding can be considered as opposite ends of a bonding continuum, or spectrum.

In a covalent bond, atoms share pairs of electrons. The covalent bond is the result of two positive nucleuses being held together by their common attraction for the shared pair of electrons. The ionic bond is the electrostatic attraction between positive and negative ions within a crystal lattice.

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Infographic poster, fact sheet and student worksheet exploring the bonding spectrum from pure covalent bonding to ionic bonding. Display the poster in your classroom or on a projector. Alternatively, print it and use as a handout.

The accompanying activity uses a variety of elements and compounds on individual cards to investigate how bonding type can gradually change. The cards are not labelled with the name of the substance, so learners need to use their knowledge of structure and bonding to arrange them in order as they answer the questions.



Electronegativity is a measure of the attraction between an atom involved in a bond and the electrons of that bond. The trends in electronegativity across the periods and down the groups of the periodic table can be explained in terms of covalent radius, nuclear charge and the screening effect of inner shell electrons.

Apart from simple covalent bonding between atoms of the same element, all bonds have some degree of covalent and ionic character. The larger the difference in electronegativities between bonded atoms, the more polar the bond will be and the greater the ionic character of the bond.

When the difference is very large, the movement of bonding electrons from the element of lower electronegativity to the element of higher electronegativity is complete, resulting in the formation of ions. Therefore, rather than isolated categories of bonding we have a bonding continuum.

Want more posters and activities on bonding?

Use this with your post-16 classes:

Try these with your 14–16 year-old learners:

Intermolecular forces

As the difference in electronegativity between the atoms in a bond goes from low to high, the strength of the forces between molecules increases. (Note: this explanation is limited to simple covalent bonding and does not include giant covalent molecules such as diamond, graphite or silica dioxide.)

Did you know…?

Hydrogen bonding is responsible for holding together macromolecules such as DNA, proteins and cellulose. It also accounts for water’s unique, life-sustaining properties as well as explaining the different boiling points of isomeric amines.

 All illustrations © Dan Bright 

More resources

  • Starter for ten quizzes that focus on bonding topics like the nature of chemical bonds, covalent bonding and properties and bonding.
  • Try these tips, contexts and activities to tackle the orbital model of the atom and bonding with our post-16 CPD series.
  • Use this Spot the bonding activity which asks learners to explore their knowledge of different bonding types, through diagrams of 18 bonds. 
  • Check students’ understanding of how properties of substances depend on their structure and bonding using this lesson plan with activities for 16–18 year olds.

This article was updated on 26 September to change the butan-1-ol structure.