In 1869, Mendeleev pushed around pieces of paper and discovered that the known elements could be grouped by their physical and chemical characteristics.
You can take a look at Mendeleleev’s table here.
The table led directly to the discovery of the elements that were “missing,” as chemists were able to look for the expected characteristics that the table predicted. The defining characteristic of an element came to be understood as its “Atomic Number” which we now know to be the number of protons in that element’s nucleus. The later discovery of the special properties of some of the elements that lay between the conductors and non-conductors, Germanium, Silicon and Gallium, would make possible semiconductor technology and ultimately spawn the information revolution.
An impressive Flash version of the periodic table can be found here.
The classic Web elements can be found here.
And you can search the periodic table from here.
No discussion of the elements would be complete if we didn’t have a listen while Tom Lehrer sings about them (at least the ones known about in 1959 when it was recorded) here.
[tags]elements,mendeleev,tom lehrer,atomic number,periodic table,germanium,silicon,gallium[/tags]