• Question: what is a atomic number?

    Asked by snowy to Damien, Rachael, Simon, Suzi, Tim on 13 Jun 2011.
    • Photo: Suzi Gage

      Suzi Gage answered on 10 Jun 2011:

      Hi @snowy, thanks for your question!
      Although I’m not a chemist/physicist, I do know the answer to your question because I recently saw a great series of programmes on TV about the elements.

      An atomic number is the number of protons (positively charged particles) which are in the nucleus of an atom (tiny particles that make up EVERYTHING that exists!). These are the numbers in the periodic table, and each atom has their own individual number. Hydrogen’s is 1, so it only has 1 proton and 1 electron (atoms always have the same number of protons and electrons). So hydrogen is really light. At the other end, there are some BIG atoms with over 100 protons (and also over 100 electrons). Some of these are so newly discovered (or created artificially) that there’s currently a big debate going on about what to call them!!!

      Hope this answers your question 🙂

    • Photo: Damien Hall

      Damien Hall answered on 13 Jun 2011:

      I can’t add much to that, because I’m not a chemist or physicist either! There’s just one thing I can say that Suzi didn’t say. Because each atom has its own individual atomic number (number of protons in the nucleus), the atomic number defines an element – the basic substances out of which everything is made. That means that atomic numbers help us keep count of how many different basic substances there are in the Universe. It blows my mind that everything that exists is made of some combination of only ninety or so basic substances!

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