The Origin of the Periodic Table I know what the periodic table looks like, but where did it come from? Whose idea was it to arrange the elements this way? In 1869, a Russian chemist named Dmitri Mendeleev came up with a way of organizing the elements that were known at the time. He set them out in order of atomic weight, and then grouped them into rows and columns based on their chemical and physical properties. 1869...that's way before the Schrödinger model, or even the Rutherford model. That's right. Mendeleev had no idea what atoms were made of or why they behaved as they did. Nevertheless, he was able to put together the periodic table almost as we know it today--except that some elements were missing, because they were unknown in 1869. Based on the gaps in his table, Mendeleev even succeeded in predicting the existence and properties of several new elements. That's pretty impressive. Can you tell me more about how Mendeleev organized the table? What kinds of properties did he use? His basic rule was this: the elements in any column, or group, of the table are similar to their column-mates. For example, look at the first column on the left, underneath hydrogen (H). The elements in this group are called the alkali metals; they're all soft metals that react violently with water to make hydrogen gas. Click here if you'd like to read more about Mendeleev's methods and the chemistry of his time.

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