1. Periodic Table
Development

2. Mendeleev’s first draft organized by increasing atomic weight.

3. Mendeleev’s published table from 1869

4. Mendeeleev’s 1871 periodic table

5. Mendeelev’s table in an 1891 publication
Lacking the noble gases

6. Using our current format, Mendeleev’s table may have looked like this

7. An updated version of Mendeleev’s table showing elements unknown to him

8. Quote
“I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and this soon convinced me that the properties of elements are in periodic dependence upon their atomic weights.” --Mendeleev, Principles of Chemistry, 1905, Vol. II

9. Discovery Dates

10. Discovery Dates
Grey -Before 1800 (38 elements): discoveries during and before the age of enlightment
Green (+22 elements): science and industrial revolutions.
Purplish (+23 elements): the age of classifying elements received the impulse of the spectrum analysis.
Bluish (+13 elements): impulse with the old quantum theory
Light Blue (+15 elements): "post atomic bomb" issues for atomic numbers 97 and above (colliders, bombardment techniques)

11. See http://en.wikipedia.org/wiki/History_of_the_periodic_table