• Question: why do some elements have two letters in the periodic table

    Asked by thesloth to Callum, Gina, Katie, Michelle, Sam on 9 Nov 2012.
    • Photo: Katie Howe

      Katie Howe answered on 9 Nov 2012:

      There are over 100 elements so there are not enough letters in the alphabet for each element to have just one letter! So usually the elements are called by their first letter (eg Hydrogen = H, Oxygen = O) or their first two letters (eg Helium=He). But sometimes they are called something totally different eg the symbol for sodium is Na (that is because the Latin name for Sodium is Natrium)

    • Photo: Sam Godfrey

      Sam Godfrey answered on 10 Nov 2012:

      Hey there,
      Basically there are 118 different elements but only 26 letters, so we have to give them different letter symbols. Sometimes these letters match up with the first two letters of the element name (like calcium is Ca) sometimes they get the letters from the old name for the element. With the newer discovered elements that are man made, they name them after famous scientists or places, so there is an element called Einsteinium which is called Es, because the scientist decided that sounds better than Ei. Strangely there is no element called E. Don’t know why.

    • Photo: Michelle Linterman

      Michelle Linterman answered on 12 Nov 2012:

      Good question. The periodic table was created a very long time ago, around 1868, by a man called Dmitri Mendeleev, he wanted to organise the elements in a way that could tell you something about their chemical properties. When he made his first table, there were 56 known elements, and these used the one or two letter codes.

      The codes themselves were first invented before the periodic table by an Englishman called John Dalton, but, only some of them looked the way they do now. Everything was in a circle, and some of the symbols looked more like pictures, for example Hydrogen was a circle with a dot in it, and sulphur was a circle with a cross in it. But, some of them were a circle with a two-letter code. Then in about 1813 a Swedish chemist called Jöns Berzelius argued that using letters only was much much easier, and these are the chemical symbols we use today in our periodic table.

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