1. The Periodic Table of the Elements

2. J.W. Dobereiner first attempted to put together a system for classifying the elements in 1827. He used the idea of the triad.

3. Dobereiner’s Triads ElementAtomic Mass Average Density Average Cl Br I 35.5 79.9 126.9 81.2 1.56 3.12 4.95 3.25 Ca Sr Ba 40.1 87.6 137.3 88.7 1.55 2.6 3.5 2.53 Note: In each case, the numerical values for the atomic mass and density of the middle element are close to the averages of the other two elements

4. John Newlands – Presented the idea of the octave in chemistry back in 1863. Was laughed out of the building. He was able to have the last laugh, however. He was awarded the Davy Medal in 1887 for his work after Mendeleev’s table was accepted and his ideas acknowledged.

5. Lothar MeyerDmitri Mendeleev Robert Bunsen “Burner”

6. Mendeleev is credited with creating the modern periodic table of the elements. He gets the credit because he not only arranged the atoms, but he made predictions based on his arrangement which were shown to be quite accurate.

11. Here is another link http://chemlab.pc.maricopa.edu/periodic/giguere.html

14. Trends Within the Periodic Table