Early Classifications of Elements: Triads, Cylindrical Table, and Octaves Explained

Early Classifications of Elements: Triads, Cylindrical Table, and Octaves Explained

• 1.
  BY: GROUP 2 EarlyClassifications Of Elements
• 2.
  LAW OF TRIADS In1829 german chemist, Johann Dobereiner noted similarity among physical and chemical properties of several groups of three elements(Triads). Middle element of each triads had an atomic weight about halfway between the atomic weights of the other two, and also the properties of the middle element were in between those of the other two members.  This seemed to work only for a few elements, it was later dismissed as coincidence.
• 3.
  DOBEREINER’S TRIAD
• 4.
  CYLINDRICAL TABLE OFELEMENTS  A.E.B de Chancourtois in 1862 arranged the then known elements in order of increasing atomic weights and made a cylindrical table of elements to display the periodic recurrence of properties. This did not attract much attention
• 5.
  LAW OF OCTAVES Englishchemist, John Alexander Newlands in 1865 arranged the elements in increasing order of their atomic weights and noted that every eighth element had properties similar to the first element.  This relationship was just like every eighth note that resembles the first in octave of music  Newlands’ law of octave seemed to be true only for elements up to calcium. He was awarded Davy medal in 1887 by Royal Society, Londen.
• 6.
  NEWLAND’S OCTAVES
• 7.
  THANK YOU