Formulae of ionic compounds (Edexcel GCSE Chemistry & Combined Science)

This lesson describes how the chemical formula of an ionic compound can be deduced using the formulae of the constituent ions. The PowerPoint and accompanying worksheet have been designed to cover point 1.26 of the Edexcel GCSE Chemistry specification and also cover the same point in the Chemistry section of the Combined Science course.

This lesson builds on the knowledge acquired in previous lessons when students learnt how to identify the charge of an ion based on the group of the atom. A step by step guide is used to show them how the transfer method can be used to write the formulae for compounds including halides and oxides. Time is taken to introduce the formulae for sulphate, carbonate, hydroxide and nitrate ions and the students are shown how brackets may be needed when writing formulae for compounds containing these ions. Understanding checks in the form of questions and quiz competitions are used to allow the students to assess their progress