We saw there lithium, then sodium and then potassium, but you didn't see rubidium, caesium and francium. Gethin: Francium. That's not an element that you hear a lot of. Miss Armit: No, it's the ...

Group 1 elements react with moist air. They are stored in oil to stop air and water vapour coming into contact with them. Moist air reacts with potassium to form potassium oxide. This creates a ...