When you get into the bath, the water level goes up – you would expect it to. But if you pour a handful of salt (for example sodium chloride) into a glass of water, the water level will go down! This is because the solvent molecules (the water molecules) become more ordered when they are near to the dissolved ions (sodium ions and chloride ions).
Having a bath has been a part of human culture for thousands of years, from Ancient Egypt to Japan. Ancient Egyptians used scented oils while bathing in the Nile, while the Romans built bathhouses with baths at different temperatures. In Japan, there is a tradition of communal bathing in hot springs known as “onsen”. In India it is believed that bathing in the Ganges river will purify the soul.
If you are in Year 9 upwards you need to be able to explain how and why ions are formed. You also need to be able to draw diagrams to show ionic bonding, and predict the formulae of ionic compounds.
To help you with this try Part 1 of our “How to work with Ionic Bonding” revision guide. It recaps what ions are, and which ions you need to remember. Included is how to draw dot and cross diagrams to represent ionic bonding. There are also some example questions and answers for you to check your understanding.
Click on the picture below to see the guide.
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