![]() Test for hydrogen with a lighted splint.Drop a small piece of lithium into a boiling tube half full of cold water (ensure that the boiling tube is not pointing at the students or yourself).Repeat the demonstration but, this time, drop the lithium onto a piece of filter paper floating on the surface of the water.Add some universal indicator to the solution.Explain that you are going to drop a piece of lithium into a trough half full of cold water.Show the experimental set up for the reaction of lithium with cold water.Stress that they need to watch and listen carefully because they are going to write a commentary about one of the reactions that they see you demonstrate. Explain their choices (select a few students).Įxplain that they are going to see you demonstrate the reaction of some alkali metals with water. ![]() Predict which of the three elements will react most vigorously with water.Use questions to draw out similarities and differences between electron arrangements. Issue traffic light cards and mini whiteboards.Īsk students to draw diagrams to show the difference in electron arrangements in atoms of lithium, sodium and potassium and ask some of them to show their ideas. Describe and explain how the alkali metals react with cold water.The reactions of lithium and sodium are demonstrated and explained the reaction of potassium is demonstrated without comment and students write an appropriate ‘voice over’ to accompany the demonstration.įinally, students predict how rubidium and caesium will react with cold water before watching the reactions on a video clip. In this activity, teacher demonstrations are used to help students learn about how alkali metals react with cold water. ![]()
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