We have seen how the simple major chord is constructed from notes 1, 3 and 5 of the major scale. More complex (extended) chords are constructed by taking further the same idea of adding alternate notes from the
major scale into the chord.
A “major 7th chord” is a major chord (1st 3rd and 5th of the major scale) with the 7th note of the major scale added making it a 4 note chord. So a C major 7th (written Cmaj7) can be played using the notes C, E, G and B. One fingering on a piano looks like this.
Here are the same 4 notes on a guitar, with
an extra E on the top string to fill the sound out.
Let’s keep going. To make a major 9th chord we keep going, so the major 9th chord (maj9)
is made up of notes 1, 3, 5, 7 and 9 of the major scale.
Hang on, there are only 7 notes in a major scale!!! Well 8 if you count the root note again.
No problem, the same scale keeps going. The 8th note of the C major scale is the root note C again, the 9th is D, the 10th is E and so on, see the piano below.
Hopefully you get the idea. Here’s a complete set of C major chords
constructed from the C major scale.
C = 1,3,5 = C,E,G
Cmaj7 = 1,3,5,7 = C,E,G,B
Cmaj9 = 1,3,5,7,9 = C,E,G,B,D
Cmaj11 = 1,3,5,7,9,11 = C,E,G,B,D,F
Cmaj13 = 1,3,5,7,9,11,13 = C,E,G,B,D,F,A
And that’s it. As you can see, the 15th note of the major scale is the root note C again, so by the time we extend as far as a Cmaj13 we are playing all 7 notes of the C major scale and have exhausted the possibilities.
Of course it’s tough to finger a 7 note chord on a 6 string guitar, so at least one of the notes has to be dropped . Which ones and why is separate topic, but you may consider that in a group situation other players will be playing notes too. For example, even if you aren’t playing the root note of a chord, the bass player most definitely will be, and fill out your stripped down version with the correct root note. This sort of thinking opens up huge possibilities when choosing fingerings for chord shapes.
That shows you all you need to know to understand how the “jazzier” sounding extended major chords are created. On the next page we’ll apply the same sort of reasoning to create the “bluesier” sounding "dominant chord" family.