colors of the Periodic Spiral

Various versions of the periodic table color the elements in different ways. Sometimes each of the four blocks is assigned a unique color. Some layouts assign different colors to those elements that are solids, liquids, and gases (at room temperature). In other versions, metals, semimetals, and nonmetals are assigned individual colors. There are a few other schemes as well. Some, for example show cesium and gallium as liquids, although only bromine and mercury are liquid at room temperature. The definitions of "metals" and "nonmetals" are, like those for gases, liquids, and solids, somewhat arbitrary, particularly when one includes the phenomenon of allotropy. Further, although the divisions among the four blocks are more sharply delineated, some theorists argue for five blocks (with H, or H and He, as a separate block). Additionally, certain of the F-block elements substitute one or two d-shell electrons where one might expect to find f electrons. Moreover, the graphic identification of the group branches (or columns, in Mendleevean terms) and periods is of equal, if not greater, importance. Although each element is unique, displaying 120 (or so) different hues would be meaninglessly redundant, aside from being impossible for the eye to differentiate. Even 18 hues, 20° apart on the color wheel—one for each chemical group—is too many, and equally redundant. A scheme that is limited to twelve hues, 30° apart on the color wheel, provides the viewer with a discernable range (although the three reds—scarlet, crimson, and magenta—are difficult for the eye to differentiate from one another, as are green and blue-green). Hence, the Periodic Spiral characterizes a given group by a progression of hues, each 120° from that assigned to the element in the period above it or below it. The Spiral displays each period in the same manner, with each element in a given period assigned a hue alternately 180° or 90° distant from the element immediately preceding or succeeding it. Lanthanum and the lanthanons, which inhabit a single period and are generally quite similar to one another in properties, are identified by a single hue for the entire series; the same is true of actinium and the actinons. As the visible spectrum begins with violet, so the Periodic Spiral begins by assigning that hue (violet blue, the B of the RGB additive primary color system) to hydrogen, the first element. Helium, the second element and the other member of the K period, is identified by the yellow hue (the Y in the CYM subtractive primary system), 180° distant from violet. Lithium, the first member of group 1, is assigned the scarlet red hue (the R in RGB) that is 120° distant from hydrogen’s violet. Green (the G in RGB), separated by 120° from both violet and scarlet, identifies sodium, the element beyond lithium in group 1, while blue (cyan blue, the C in CYM) identifies beryllium, the second element of the second period. And so on. The validity of this scheme may extend only to its usefulness in a graphic representation the periodic law. That said, there is no harm in having some fun exploring the twelve "color sets" of elements that this scheme implies, but the following paragraphs are meant to be taken with a grain of sodium chloride…