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Research about Döbereiner, Newlands and Mendeleev's discoveries

  • Döbereiner arranged groups of three elements with similar properties into ‘triads'.
  • Newlands and Mendeleev arranged the elements in order of increasing relative atomic mass.
  • Newlands did not leave any space for undiscovered elements but Mendeleev did. 
  • Using Newlands table, Mendeleev was able to successfully predict the properties of three elements that were not yet discovered.

Döbereiner's triads

A German scientist called Johann Döbereiner put forward his law of triads in 1817. Each of Döbereiner's triads was a group of three elements. The appearance and reactions of the elements in a triad were similar to each other.

Döbereiner discovered that the relative atomic mass of the middle element in each triad was close to the average of the relative atomic masses of the other two elements. This gave other scientists a clue that relative atomic masses were important when arranging the elements.

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