The Periodic Table of the Elements

Mendeleev's original table:

Mendeleev's table had several empty places. He asserted that new elements would be found to fill them, and -- this is important -- predicted the properties that they ought to have.

On the Relationship of the Properties of the Elements to their Atomic Weights D. Mendelejeff, Zeitscrift für Chemie 12, 405-406 (1869); translation by Carmen Giunta
One can predict the discovery of many new elements, for example analogues of Si and Al with atomic weights of 65-75.
(Mendeleev's later paper, published in 1871, went into more detail. For example, Mendeleev predicted that "eka-aluminum" would have a density of 5.9 grams per cc)


  
  Q:  His "eka-aluminum" was discovered in 1875, 
      just a few years after the prediction.
      Its density turns out to be 5.91 grams per cc.
      What do we now call it?


  Q:  His "eka-silicon" was discovered in 1886.
      What do we now call it?

Mendeleev's improved table:

A simple line graph of ionization energy versus atomic number, from Modern Physics by Kenneth Krane (John Wiley and Sons, 1996).

One can show the ionization energy as the altitude above the element's location on the periodic table with a 3-D graph; this one comes from The Periodic Kingdom, by P. W. Atkins (BasicBooks, 1995).

One can even create imaginary landscapes using the same idea that altitude = ionization energy, although the example below comes close to being a gratuitous use of computer graphics (it comes from the Visual Interpretation of the Table of the Elements website). Note that the point of view is identical to that of the previous example: from the southwest corner of the kingdom.

For more information

Some early versions of the periodic table:
- 1869
- 1871
- 1872
Historical notes on Mendeleev's first periodic table
A real periodic TABLE , literally.
I really enjoyed reading the book The Periodic Kingdom, by P. W. Atkins. It provides detailed explanations of the history, construction, and interpretation of the periodic table. You can find it on Amazon.com
Oliver Sacks' book Uncle Tungsten gives a loving look back at the author's teenage fascination with chemicals of all kinds. It includes a great deal of history and background on the discovery of elements.
If you are in the mood for some real lit-er-a-ture, and don't mind being depressed, read Primo Levi's book The Periodic Table. Each of the chapters describes an episode of Levi's life before and during the Second World War, but involves a crucial plot element (yes, that is what I meant to write).
Who could forget Tom Lehrer singing The Elements? (or a direct URL to the visual version.
Can't remember what tellurium is? Perhaps the Periodic Table of Haiku would help.