1. A Bird's-Eye View of the Periodic System

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Stories About Chemistry

1. A Bird's-Eye View
of the Periodic System

A fleeting glance, a first impression, is usually of little value. Sometimes it leaves the observer indifferent, sometimes it surprises him. Once in while it makes him exclaim, like the hero of the well known anecdote when he saw the giraffe at the Zoo: "It can't be true!" But even a first acquaintance with a thing or a phenomenon, a bird's-eye view of it, if you like, is often useful.

Mendeleyev's Periodic System of Elements can hardly be called a thing or a phenomenon. It is rather a kind of mirror reflecting the essentials of one of the greatest laws of nature, the Periodic Law. This is a code of behaviour obeyed by the hundred odd elements found on Earth or produced artificially by man, a set of regulations, as it were, prevailing in the Big House of the chemical elements. A first glance at this house reveals a great deal. The first feeling is one of surprise, as if in the midst or standard large-panel buildings we suddenly saw a house of whimsical but elegant architecture.

What is it that is surprising about Mendeleyev's Table? To begin with, the fact that its periods, its storeys, have different floor plans. (Unlike ordinary houses, the "storeys" of Mendeleyev's Big House (Periodic System) should be numbered from top to bottom, because any new "storey" that might have to be added to accommodate new elements would have to be attached to the bottom of the table.)