Lesson 20 - Introduction to seventh chords
Part I - Seventh chords
Seventh chords are comprised of four notes. The base notes are the triad. The chord derives its name from the distance between the outer two notes. Because of the extra note, naming the quality of the chord becomes more difficult than with a triad. Tis is because there are multiple qualities of 7ths and of triads. The first step is to identify the quality of the triad. Next is to identify the quality of the 7th. For example, if the triad is Major, and the 7th is minor, the 7th chord is Major-minor. All of the possible 7th chords are:
1. Major-Major
2. Major-minor
3. Major-Augmented
4. Major-diminished
5. minor-Major
6. minor-minor
7. minor-diminished
8. minor-augmented
9. diminished-major
10. Diminished-minor
11. Diminished-diminished
12. Diminished-augmented
13. Augmented-major
14. Augmented-minor
15. Augmented-diminished
16. Augmented-augmented
Fig.1 All types of seventh chords
Fortunately, most of these are not used very commonly.
Common nicknames:
1. Major-major seventh (often called a Major seventh)
2. Major-minor seventh (often called a dominant seventh)
3. minor-minor seventh (often called a minor seventh)
4. Diminished-minor seventh (often called half-diminished seventh)
5. Diminished-diminished seventh (often called fully-diminished seventh)
Part II - Inversion of seventh chords
It is possible to rearrange the notes of a seventh chord to form an inversion. With seventh chords, it is possible to have root position, first inversion, second inversion, and third inversion. In every case, an inverted 7th chord will have an interval of a second present, and the upper note will ALWAYS be the root of the chord.
Figured bass for seventh chords are as follows:
Fig.2 inversion of seventh chords
Part III- diatonic seventh chords in the Major scale
Here, figure thee has the diatonic seventh chords of the Major scale. and figure 4 has the most commonly used seventh chords of the major scale.
Fig.3diatonic seventh chords of the major scale
Fig.4 commonly used seventh chords of the major scale
Notice the vii half diminished seventh has the diminished symbol with a slash through it to signify half diminished.
Part IV - diatonic seventh chords of the minor scale
Fig.5 diatonic chords of the minor scale
Fig.6 commonly used seventh chords of the minor scale
Here, the vii fully diminished seventh is more common also, notice how the ii half diminished is more common.
