In addition to diatonic triads, every major and minor scale has seven diatonic seventh chords.
Let's examine the diatonic seventh chords of the C major scale.
First, construct the scale.
Next, stack three generic thirds on top of each note.
Finally, analyze the resulting seventh chords.
The first chord is C – E – G – B, a major triad and a major seventh. Therefore, it is a major seventh chord.
The second chord is D – F – A – C, a minor triad and a minor seventh. Therefore, it is a minor seventh chord.
The third chord is E – G – B – D, a minor triad and a minor seventh. Therefore, it is also a minor seventh chord.
The fourth chord is F – A – C – E, a major triad and a major seventh. Therefore, it is a major seventh chord.
The fifth chord is G – B – D – F, a major triad and a minor seventh. Therefore, it is a dominant seventh chord.
The sixth chord is A – C – E – G, a minor triad and a minor seventh. Therefore, it is a minor seventh chord.
The seventh chord is B – D – F – A, a diminished triad and a minor seventh. Therefore, it is a half-diminished seventh chord.
The eighth chord is a repetition of the first (C – E – G – B), making it a major seventh chord.
The first seventh chord of a major scale will always be a major seventh, the second and third seventh chords will always be minor sevenths, etc.
Next, we will uncover the diatonic seventh chords of the C Natural Minor scale.
First, construct the scale.
Again, stack three generic thirds.
Finally, let's analyze the resulting seventh chords.
The first chord is C – Eb – G – Bb, a minor triad and a minor seventh. Therefore, it is a minor seventh chord.
The second chord is D – F – Ab – C, a diminished triad and a minor seventh. Therefore, it is a half-diminished seventh chord.
The third chord is Eb – G – Bb – D, a major triad and a major seventh. Therefore, it is a major seventh chord.
The fourth chord is F – Ab – C – Eb, a minor triad and a minor seventh. Therefore, it is minor seventh chord.
The fifth chord is G – Bb – D – F, a minor triad and a minor seventh. Therefore, it is also a minor seventh chord.
The sixth chord is Ab – C – Eb – G, a major triad and a major seventh. Therefore, it is a major seventh chord.
The seventh chord is Bb – D – F – Ab, a major triad and a minor seventh. Therefore, it is a dominant seventh chord.
The eighth chord is a repetition of the first (C – Eb – G – Bb), making it a minor seventh chord.
Next, we will discuss the diatonic seventh chords of harmonic minor.
To convert natural minor to harmonic minor, the seventh tone is raised a half step. Therefore, each Bb (the seventh tone of C minor) is raised to a B.
To convert natural minor to harmonic minor, the seventh tone is raised a semitone. Therefore, each Bb (the seventh tone of C minor) is raised to a B.
Each chord which contained a Bb needs to be reanalyzed.
The first chord is now C – Eb – G – B, a minor triad and an major seventh. Therefore, it is minor-major seventh chord.
The third chord is now Eb – G – B – D, an augmented triad and an major seventh. Therefore, it is augmented-major seventh chord.
The fifth chord is now G – B – D – F, a major triad and a minor seventh. Therefore, it is a dominant seventh chord.
The seventh chord is now B – D – F – Ab, a diminished triad and a diminished seventh. Therefore, it is a fully-diminished seventh chord.
The eighth chord is a repetition of the first (C – Eb – G – Bb), making it a minor-major seventh chord.
Finally, we will discuss the diatonic seventh chords of melodic minor.
To convert harmonic minor to melodic minor, the sixth tone is raised a half step. Therefore, each Ab (the sixth tone of C minor) is raised to an A.
To convert harmonic minor to melodic minor, the sixth tone is raised a semitone. Therefore, each Ab (the sixth tone of C minor) is raised to an A.
Each chord which contained an Ab needs to be reanalyzed.
The second chord is now D – F – A – C, a minor triad and an minor seventh. Therefore, it is a minor seventh chord.
The fourth chord is now F – A – C – Eb, a major triad and a minor seventh. Therefore, it is a dominant seventh chord.
The sixth chord is now A – C – Eb – G, a diminished triad and a minor seventh. Therefore, it is a half-diminished seventh chord.
The seventh chord is now B – D – F – A, a diminished triad and a minor seventh. Therefore, it is also a half-diminished seventh chord.
Use this chart to reference the diatonic seventh chords in each scale.