• Question: How many atoms are there in the world

    Asked by matty23 to Adam, Catherine, Karen, Leila, Nazim on 15 Mar 2012. This question was also asked by nezza.
    • Photo: Adam Stevens

      Adam Stevens answered on 14 Mar 2012:


      12 grams of Carbon contains 6.0221415 × 10^23.

      That’s more than 600000000000000000000000000 atoms.

      The earth has a mass of 5.9742 × 10^24 kg

      That’s more than 500000000000000000000000000000000 grams.

      Multiply them together and you get about
      100000000000000000000000000000000000000000000000000000000000000 atoms.

      Hope that helps!

    • Photo: Leila Battison

      Leila Battison answered on 15 Mar 2012:

      And that’s not even counting all the plants, animal, and bacteria that live on the surface of the world, and the atoms in the atmosphere!

      More than you can even begin to imagine!

    • Photo: Karen Masters

      Karen Masters answered on 15 Mar 2012:

      Oooh a great question for practising estimating things….

      Well. The Earth weighs 6×10^24 kg (that’s 6000000000000000000000000 kg) according to Google. It’s mostly made of rock I think… hmm interesting.

      Well this article (http://www.universetoday.com/15048/what-is-the-earth-made-of/) says the Earth is 30% iron, 30% oxygen, 15% silicon and 15% magnesium (roughly).

      Now for more Google which says the atomic mass of iron is 55 g (ie. 1 mole of iron atoms weigh 55g), oxygen is 16g, silicon is 28g and magnesium 24g.

      Do you know what a mole is I wonder – it’s just a definition of a weighable amount of atoms. 1 mole of atoms is 6×10^23 atoms.

      2×10^24 kg of iron, or 4×10^25 moles (mass/mass of a mole) or 2×10^49 atoms of iron
      2×10^24 kg of oxygen, or 1×10^26 moles, or 6×10^49 atoms of oxygen
      1×10^24 kg of silicon, or 2×10^49 atoms
      1×10^24 kg of magnesium, or 2×10^49 atoms.

      Add it together and it’s 1×10^50 atoms by my estimate. That’s

      1 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000 atoms.

      That’s a lot!

      Did you know that in some sense a neutron star is just once single massive city sized atom (made of just neutrons).

    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 18 Mar 2012:

      Look at a beach and see the grains of sand: there are a lot more atoms in your body, than there are grains of sand on that beach.

      I can’t even begin to imagine how many atoms there are in the world!