Major scale will generally reflect the accidentals in the corresponding major scale. For instance, if a piece of music is in E major, then the seven pitches in the E major scale (E, F, G, A, B, C and D) are considered diatonic pitches, and the other five pitches (E, F/G, A, B, and C/D) are considered chromatic pitches. In this case, the key signature will have three flats (B, E, and A). The figure below shows all 12 relative major and minor keys, with major keys on the outside and minor keys on the inside arranged around the circle of fifths.
Diatonic scale the ancient Greeks. In musical set theory, Allen Forte classifies diatonic scales as set form 7–35. This article does not concern alternative seven-note diatonic scales such as the harmonic minor or the melodic minor. Western music from the Middle Ages until the late 19th century (see common practice period) is based on the diatonic scale and the unique hierarchical relationships created by this system of organizing seven notes. There is one claim that the 45,000-year-old Divje Babe Flute uses a diatonic scale, but there is no proof or consensus it is even a musical instrument. There is evidence that the