Seventh chords extend thirds above triads, so the root, third, fifth, and seventh are all used. A world of sonic possibilities is revealed when you add another interval to the triad.
Common 7th Chords
Seventh chords are described using both the quality of the triad and the quality of the seventh. The common seventh chords are:
- Major (MM7)
- minor (mm7)
- Dominant (Mm7)
- Half-diminished (ø7)
- diminished (o7)
7th Chords in Major and Minor Keys
In Major keys, the diatonic 7th chords are:
Major – minor – minor – Major – Dominant – minor – half-diminished.
When the 5th and 7th chords In minor keys fulfill the dominant function these chords are Dominant and diminished, respectively. This functionality is achieved by raising the leading tone. In this setting, the chords are:
minor – half-diminished – Major – minor – Dominant – Major – diminished.
All minor scales do not create the same chords. Different scale degrees are raised or lowered based on the context and the sound that the musician or arranger is trying to achieve. The dominant function is present in the Harmonic Minor Scale but the I and iii chords are also raised.
7th Chords as Figured Bass
