Chemistry for Everyone
Chemistry of Art and Color Sudoku Puzzles
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Michael J. Welsh Science and Mathematics Department, Columbia College, Chicago, IL 60605-1996;
[email protected] The precursor of the sudoku puzzle was first published in the United States in 1979 by Howard Garns, a retired architect and freelance puzzle constructor. In April 1984, the puzzle was introduced in Japan and the name “sudoku” was assigned to the puzzle. “Suuji wa dokushin ni kagiru” may be translated as “the numbers must be single” or “the numbers must occur only once”. Later the name was abbreviated to sudoku (pronounced SUE-dough-coo; “su” means number, “doku” means single). In April 2005, The New York Post published sudoko puzzles as a regular feature and by July 2005, the puzzle surged in popularity all over the country (1, 2). The puzzles are popular with Columbia College Chicago students as well. In order to capitalize on the craze, three
sudoku puzzles were created that use light science and chemistry terms taught in a nonmajor course, Chemistry of Art and Color. Sudoku puzzles are based on six unique terms (for a 6 × 6 puzzle) or nine unique terms (for a 9 × 9 puzzle) used only once in a row, column, or box. The commonly used symbols are the Arabic numerals 1–6 or 1–9. By replacing the Arabic numerals with symbols used in class, unique sudoku chemistry puzzles were created. Sudoku is a puzzle of logic and reason. The classic sudoku puzzle is a number puzzle consisting of 9 × 9 grid (or a simpler 6 × 6 grid), divided into nine 3 × 3 boxes (or six 2 × 3 boxes). Some of the numbers are placed in the squares of the grid as “clues”. The object of the puzzle is to
Figure 1. Sudoku puzzle 1 using symbols for colors—the primaries of light: red (R), green (G), and blue (B); and pigment or dye primaries: cyan (C), magenta (M), and yellow (Y).
Figure 2. Sudoku puzzle 2 using symbols of nine of the fourth period transition metal elements (Ti through Zn).
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Chemistry for Everyone
fill in the remaining squares of each row, column, and box with the digits 1–9 (or 1–6) so that each row contains all the numbers from 1–9 (or 1–6), each column contains all the numbers from 1–9 (or 1–6), and each 3 × 3 box (or 2 × 3 box) contains all the numbers from 1–9 (or 1–6). However, each of the numbers 1–9 (or 1–6) can appear only once on each row, column, and box. The number of “clues” and their location in the puzzle determines the difficulty of the puzzle. Each number in the solution therefore occurs only once in each of three directions, hence the “single symbols” implied by the puzzle’s name. The puzzles developed here use unique symbols taken from science and chemistry instead of the usual Arabic numerals. The first of the three puzzles (shown in Figure 1) is a simple 6 × 6 sudoku puzzle using symbols for the primary colors of light—red (R), green (G), and blue (B)—and the primary colors of pigments and dyes—cyan (C), magenta (M), and yellow (Y)—for the six unique symbols. The second puzzle (see Figure 2) was made using symbols of chemical names from nine of the fourth period tran-
sition metal element symbols (Ti through Zn, which appear in many traditional pigments) to create a 9 × 9 puzzle more difficult than the first one. The last puzzle, shown in Figure 3, was made using general formulas for nine organic functional groups typically found in dyes and paint media, creating a 9 × 9 puzzle that is the most difficult of the three. W
Supplemental Material
The three Chemistry of Art and Color Sudoku puzzles and their solutions (on a separate page) are available in this issue of JCE Online. Literature Cited 1. Wikipedia, the Free Encyclopedia. Sudoku. http://en. wikipedia.org/wiki/Sudoku (accessed Jan 2007). 2. Galanti, Gil. Conceptis Puzzles. http://www.conceptispuzzles. com/articles/sudoku/ (accessed Jan 2007).
Figure 3. Sudoku puzzle 3 using general formulas for organic functional groups.
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Vol. 84 No. 4 April 2007
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