• Question: How many atoms are in a human

    Asked by anon-293704 to Christopher on 13 May 2021.
    • Photo: Christopher Todd

      Christopher Todd answered on 13 May 2021:

      The average human cell contains around 100 trillion atoms (depending on the size).
      The average human body contains around 30 trillion cells (again this can be different depending on how big the person is).

      This means in the average human body there are around 3 octilion atoms!!! That 3 with twenty seven zeros after it (and not a number I get to use often).

Comments

  • Photo: Philip

    Philip commented on :

    I estimate that its around 6 octillion. This is based on water having 3 atoms and we are mostly water! I assume the average human is 70kg, so we have 70000/18= 3889 moles of water (waters molar mass is 18g per moles). 1 mole of any substance has 6.022Exp23 molecules (this is Avogadro’s number). So 70kg of water has 3889×6.022Exp23= 2.34Exp27 (2 octillion) molecules. Water has 3 atoms, so we have about 3×2= 6 octillion atoms in the average human!. Did you know that the first estimate for Avogadros number was made in 1646 by a Monk who burned some perfume in a church and estimated it from the size of his nose!! quite amazing science for its time!

  • Photo: Sujit

    Sujit commented on :

    Good question. Maybe two handfuls of sand.