Harmonising The Major Scale 3rds and 7ths

In music, a triad is a set of three notes that can be stacked in thirds.

When stacked in thirds, the triad’s members, from lowest pitched tone to highest, are called:

  • the Root
  • the Third - its interval above the root being a minor third (three semitones) or a major third (four semitones)
  • the Fifth - its interval above the third being a minor third or a hence its interval above the root being a diminished fifth (six semitones), perfect fifth(seven semitones)

Harmonizing the Major scale 3rds

seventh chord is a chord consisting of a triad plus a note forming an interval of a seventh above the chord’s root. When not otherwise specified, a “seventh chord” usually means a dominant seventh chord: a major triad together with a minor seventh. However, a variety of sevenths may be added to a variety of triads, resulting in many different types of seventh chords, as described below.


Harmonizing the Major scale_7ths