Extended Chords: Different Types & How They’re Formed 7th Chords.
Extended 7th chords are simply chords that have notes which extend further than the standard three note triad. They’re formed by stacking thirds on top of the base triad.
Extended chords provide another layer of sound above general major and minor triads. They can add that extra spice that a song needs or can be that mystery chord that you can’t quite figure out when learning a song by ear. The ‘extended’ portion of the chords are the extra thirds which are stacked above the base triad. Remember, triads are formed by stacking the 1st, 3rd, and 5th degrees of the scale.
To make a seventh chord you start with the base triad and add the 7th scale degree on top. Whether that added third is major or minor is dependent on the type of 7th chord. For all of the examples I have featured the A and the D major and Minor triad chord shapes.
Major 7th Chords:
The major 7th chord is a major triad with a major third stacked on the top. The sound of the major 7 chord is open and airy, it’s used very regularly in jazz.
Minor 7th Chords:
To construct a minor 7 chord take a minor triad and add another minor third on top.
The minor 7 chord occurs diatonically as a iim7, iiim7, & vim7 in a major key and im7, ivm7, & vm7 in a minor key. Basically, any diatonic minor chord could also be played as a minor 7 chord and still sound right.
Dominant 7th Chords:
The dominant 7th chord is a major triad with a minor third stacked on top of it. It’s natural tendency is to resolve a fourth down. It’s used a lot in blues and jazz
Dominant 7th chords occur diatonically as a V7 in all major keys and can be played non-diatonically as a V7 in minor keys. Additionally, when playing a standard twelve bar blues progression it’s quite common to use a dominant 7 for all chords in the progression.
The non-extended diatonic V triad is called the dominant chord, which is where the dominant 7th gets it’s name.
In part 2 we will look at 9th chords