• Question: Why is the periodic table set out the way it is?

    Asked by to Daren, Lynne, Phillip, Simon on 18 Jun 2014. This question was also asked by .
    • Photo: anon

      anon answered on 18 Jun 2014:

      Because Dimitri Mendeleev noticed that there were similarities between certain elements so put them together in groups (theses are the columns in the periodic table) and rows (these are called periods, hence periodic table).

      He did this before anybody knew about the number and layout of the electrons in each element and it turns out he was right. (atoms are made up of three different types of particle – electrons, protons and neutrons). Electrons are arranged in layers around the protons and neutrons. The number of electrons increase by one as you go across the rows in the periodic table.The elements have the same number of electrons in their outer layer as you go down a group.

    • Photo: Lynne Thomas

      Lynne Thomas answered on 18 Jun 2014:

      Jenny has answered this really well. It is a really useful guide for us as scientists though as where the elements are in the periodic table tells a lot about how they will behave. So for instance the column furthest to the right contains elements called the noble gases and these are very unreactive. Whereas the elements in the first column are very reactive. It is all to do with where the electrons are around the atoms. Chemistry is basically about what happens to the electrons around the atoms so the number of them is very important!

      Its also interesting to note that because Mendeleev found this pattern, scientists could predict elements which they hadn’t yet found and they could then design experiments to try and find them!

    • Photo: Daren Fearon

      Daren Fearon answered on 18 Jun 2014:

      Jenny and Lynne have answered this question very well. Mendeleev did a great job creating this table and predicting the existence of elements that weren’t known to exist!

      Lots of people suggested alternative versions of the periodic table and they probably thought Mendeleev’s version wasn’t very good as it had loads of holes. But in the end the discovery of new elements that supported Mendeleev meant we now know consider his version correct. Good work, Mendeleev.

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