Scales and sonorities of the 20th Century
The Whole tone scale
This scale only consist of 6 tones, major seconds and a diminished third (which sounds like a major second). We only have 2 whole tone scales, any transposition or mode will just duplicate the pitch contents. Some theorists have classified in their analysis this scale as WT0 (whole tone 0) and WT1 (whole tone 1); the main difference is that the first one (WT0) the natural pitches are C-D-E and the other ones with accidentals, while the second one (WT1) would be on the contrary (C#-D#-E#).
The harmonic spelling of notes is not important; in the first example instead of F#-G#-A# we could write it as Gb-Ab-Bb. The Whole tone scale is usually related to the Impressionisms period and to Claude Debussy (1862-1918). This type of scale is harmonically limited because it is impossible to build mayor or minor triads and the only seventh chord we could create are the dominant 7th but with his diminished 5th, in other words, the French augmented sixth, or with the augmented 5th. On the other hand, this tonal ambiguity allows the composer to create chord blocks sonorities in order to compensate for the mayor and minor chords.
Whole tone Scale, teoría's Book of Scales