• Question: what is the most explosive alkali metal?

    Asked by anon-193363 to Jamal, iainstaniland, Carl on 5 Nov 2018.
    • Photo: Iain Staniland

      Iain Staniland answered on 5 Nov 2018:

      I would guess at Cesium having read about these alkali metals on the web. It is not something that I would like to have to use in a lab as apparently it can explode just by coming into contact with air!
      At school I remember the teacher showing us potassium and lithium reacting with water although the small amounts burnt with a bright flame rather than exploding.
      We use Lithium (an alkali metal) batteries in our logging devices, just like in mobiles phones. Because of the violent and explosive reaction with water and the fact that these loggers have to work in the sea they are protected by a hard resin casing (usually epoxy resin). They are tested to extremes of cold/heat and pressure so that the battery is kept safe and has no chance of exploding!

    • Photo: Carl Heron

      Carl Heron answered on 5 Nov 2018:

      Iain is correct. It’s caesium. Caesium is far too explosive to demonstrate at school. Your chemistry teacher might show you how sodium and potassium fizz and sputter in water. One interesting fact: Caesium was discovered by Robert Bunsen and his colleague, Gustav Kirchhoff. Bunsen’s name is remembered in virtually every chemistry laboratory in the world (as in Bunsen burner).

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