Diatonic Seventh Chords

In addition to diatonic triads, every major and minor scale has seven diatonic seventh chords. In the next example, we will find the diatonic seventh chords of the C Major Scale. First, start with the diatonic triads. Next, stack a generic third on top of each triad. Finally, analyze the resulting seventh chords.

The first chord is a major triad and a major seventh. Therefore, it is a major seventh chord. The second chord is a minor triad and a minor seventh. Therefore, it is a minor seventh chord. The third chord is a minor triad and a minor seventh. Therefore, it is also a minor seventh chord. The fourth chord is a major triad and a major seventh. Therefore, it is a major seventh chord. The fifth chord is a major triad and a minor seventh. This combination makes it a dominant seventh chord. The sixth chord is a minor triad and a minor seventh. Therefore, it is a minor seventh chord. Chord number seven is a diminished triad and a minor seventh. Therefore, it is a half-diminished seventh chord. Finally, the last chord is the same as the first.

Next, we will analyze the diatonic seventh chords of the C natural minor scale. The first chord is a minor triad and a minor seventh. Therefore, it is a minor seventh chord. The second chord is a diminished triad and a minor seventh. Therefore, it is a half-diminished seventh chord. The third chord is a major triad and a major seventh. Therefore, it is a major seventh chord. The fourth chord is a minor triad and a minor seventh. Therefore, it is a minor seventh chord. The fifth chord is a minor triad and a minor seventh. Therefore, it is also a minor seventh chord. The sixth chord is a major triad and a major seventh. Therefore, it is a major seventh chord. Chord number seven is a major triad and a minor seventh. Therefore, it is a dominant seventh chord. Again, the last chord is the same as the first.

Finally, we will analyze the diatonic seventh chords of the C harmonic minor scale. Since the first chord contains a minor triad and major seventh, it doesn't fit any of the seventh chords that we have learned. Since the third chord contains an augmented triad, it also doesn't fit. These two chords are rarely used. The fifth chord now contains a major triad and a minor seventh. Therefore, it is a dominant seventh chord. Finally, chord number seven contains a diminished triad and a diminished seventh. Therefore, it is a diminished seventh chord.

We will now discuss the analysis symbols for diatonic seventh chords. Recall the symbols for the harmonic minor diatonic triads. We simply add a small seven to the top right corner of each roman numeral. If the seventh chord is half diminished, a slash is placed through the circle.