In music, a whole tone scale is a scale in which each note is separated from its neighbours by the interval of a whole tone. In twelve-tone equal temperament, there are only two complementary whole tone scales, both six-note or hexatonic scales:
The whole tone scale has no leading tone and because all tones are the same distance apart, "no single tone stands out, [and] the scale creates a blurred, indistinct effect". This effect is especially emphasised by the fact that triads built on such scale tones are all augmented triads. Indeed, all six tones of a whole tone scale can be played simply with two augmented triads whose roots are a major second apart. Since they are symmetrical, whole tone scales do not give a strong impression of the tonic or tonality.
The composer Olivier Messiaen called the whole tone scale his first mode of limited transposition. The composer and music theorist George Perle calls the whole tone scale interval cycle 2, or C2. Since there are only two possible whole tone scale positions (that is, the whole tone scale can be transposed only once), it is either C20 or C21. For this reason, the whole tone scale is also maximally even and may be considered a generated collection.
Due to this symmetry, the hexachord consisting of the whole-tone scale is not distinct under inversion or more than one transposition. Thus many composers have used one of the "almost whole-tone" hexachords, whose "individual structural differences can be seen to result only from a difference in the 'location', or placement, of a semitone within the otherwise whole-tone series." Alexander Scriabin's mystic chord is a primary example, being a whole tone scale with one note raised a semitone, this alteration allows for a greater variety of resources through transposition.
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In 1662, Johann Rudolf Ahle wrote a melody to the lyrics of Franz Joachim Burmeister's "Es ist genug" (It is enough), beginning it with four notes of the whole tone scale on the four syllables. Johann Sebastian Bach chose the chorale to end his cantata O Ewigkeit, du Donnerwort, BWV 60, set for four parts.
Mozart also used the scale in his Musical Joke, for strings and horns. In the 19th century, Russian composers went further with melodic and harmonic possibilities of the scale, often to depict the ominous; examples include the endings of the overtures to Glinka's opera Ruslan and Lyudmila and Borodin's Prince Igor, and the Commander's theme in Dargomyzhsky's The Stone Guest. Further examples can be found in the works of Rimsky-Korsakov: the sea king's music in Sadko and also in Scheherezade:
(For some short piano pieces written completely in whole-tone scale, see Nos. 1, 6, and 7 from V.A. Rebikov's Празднество (Une fête), Op. 38, from 1907.) H. C. Colles names as the "childhood of the whole-tone scale" the music of Berlioz and Schubert in France and Austria and then Russians Glinka and Dargomyzhsky. Claude Debussy, who had been influenced by Russians, along with other impressionist composers made extensive use of whole tone scales:
For this prelude, Debussy asks the pianist to play "dans un rythme sans rigueur at caressant". The sense of mystery and ambiguity here even extends to the title of the piece, which translates either as "sails" or "veils".
"Janáček’s free chromaticism never loses touch with a diatonic scale for long. Though the whole-tone scale is prominent in much of his music after 1905 when he encountered Debussy, it serves simply to fit the motifs over augmented chords. The same motifs return from the whole-tone to the diatonic scale without emphasizing the contrast."
The first of Alban Berg's Seven Early Songs opens with a whole-tone passage both in the orchestral accompaniment and in the vocal line that enters a bar later. Berg also quotes the Bach chorale setting referred to above in his Violin Concerto. The last four notes of the 12-tone row Berg used are B, C♯, E♭ and F, which, together with the first note, G, comprise five of the six notes of the scale.)
Béla Bartók also uses whole-tone scales in his fifth string quartet. Ferruccio Busoni used the whole tone scale in the right hand part of the "Preludietto, Fughetta ed Esercizio" of his An die Jugend, and Franz Liszt applied the whole tone scale to parts of the score of his Dante Symphony (1857), and had used the technique as early as 1831, in the Grande Fantaisie sue La clochette.
An early instance of the use of the scale in jazz writing can be found in Don Redman’s "Chant of the Weed" (1931). In 1958, Gil Evans recorded an arrangement that gives striking coloration to the "abrupt whole-tone lines"  of Redman's original. Wayne Shorter's composition "JuJu" (1965), features heavy use of the whole tone scale, and John Coltrane's "One Down, One Up" (1965), is built on two augmented chords arranged in the same simple structure as his earlier tune "Impressions".
However, these are only the most overt examples of the use of this scale in jazz. A vast number of jazz tunes, including many standards, use augmented chords and their corresponding scales as well, usually to create tension in turnarounds or as a substitute for a dominant seventh chord. For instance a G7 augmented 5th dominant chord in which G altered scale tones would work before resolving to C7, a tritone substitution chord such as D♭9 or D♭7♯11 is often used in which D♭/G whole tone scale tones will work, the sharpened 11th degree being a G and the flattened 7th being a C♭, the enharmonic equivalent of B, the major third in the G dominant chord.