• Question: I know that an atom is the smallest particle that can survive on its own, but I have also learned that there are lots of different types of atoms, so which is the smallest atom?

    Asked by katiemcgorryy to Aled, Ellie, Fiona, Kev, Willem on 12 Mar 2014.
    • Photo: Aled Roberts

      Aled Roberts answered on 12 Mar 2014:

      Hi Katiemcgorryy!

      If we take smallest in the sense of the atom with the least mass then it would have to be hydrogen which sits at the start of the periodic table! If we were to take smallest to mean size then it might be helium with a diameter measuring about 31-32 picometers!!!! (compared to hydrogen which is 53 picometers!).

      For reference 1 picometer = 1 trillionth of a meter!! (1 / 1,000,000,000,000!)

      Hope that answers your question! 🙂

    • Photo: Willem Heijltjes

      Willem Heijltjes answered on 12 Mar 2014:

      Hydrogen. It has just one proton and one electron – that’s why its number one in the periodic table!

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