Ionic Formula Builder
Choose how many of each ion you need until the charges cancel, and watch the formula build itself.
About this activity
Ten ionic compounds, from sodium chloride to aluminium sulfate. Students change the number of each ion with + and − buttons while a counter adds up the positive and negative charge, so they can see when the compound has no overall charge. Wrong checks get a hint, brackets are explained when they appear, and two questions at the end are done without the builder. The compounds change every time. The first screen says where this sits in the student’s exam board (GCSE Chemistry and Combined Science on AQA, Edexcel and OCR).
How to use Ionic Formula Builder
- Ionic Formula Builder is a free Chemistry activity for Years 10 to 11 that takes about 10 minutes. Try it on this page on a computer, tablet or phone: there’s nothing to download.
- In a lesson, choose Show on the board to play it together as a class.
- To set it for a class, a teacher shares it and gets a code: students type the 6-digit code at lycolearn.co.uk/join with their first name and the first letter of their surname (no accounts needed), and their scores come back to the teacher.
Students will
- Work out the formula of an ionic compound from the charges on its ions
- Use the smallest whole numbers of each ion
- Use brackets for more than one of an ion made of several atoms
Teaching tips
- Good straight after teaching ionic bonding: the charge counter makes “the charges must cancel” visible.
- Ask students to say the rule for brackets in their own words after calcium hydroxide.