Where is the 7th Chord in the Chord Family Lineup?

In our Uke Camp lessons, we learned about the notes and chords within a key. For instance, the notes in the key of C major are C D E F G A B, and those letters also have a number: C=1 D=2 E=3 F=4 G=5 A=6 B=7. We also learned that the chords within a chord family based on these notes can have both major and minor chords:

C Dm Em F G Am Bdim

There are no 7th chords in that line-up!

Seventh chords can be included in a chord family and are very helpful as transition notes that pull us back to the root chord. In this instance, the 7th is always based on the V (5) chord. In the key of C major Chord Family the G is the V (5) chord, so the G7 can be used in place of the G major chord to help with that transition sound - moving the music forward to the next chord.

These chords can be interchangeable within the key of C and each has a unique sound that “moves” the music in slightly different ways. For instance, when we played Jambalaya, we moved from C to G7 and back to C. Try that with C G C and see if you can hear the difference. The G7 seems to “pull” back to the C more strongly than the G.

There is another instance when a 7th chord is used instead of a chord within a chord family. When this happens we are using a 7th chord that is not part of the key but is replacing one of the key’s minor chords - the ii (2), iii (3), or vi (6). This is an unusual sound that changes the character of the music. Try these two examples and listen to how the character of the music changes!

Key of G major progressions using minors or sevenths:

G Em Am D (minors)
G E7 A7 D (7ths replacing the minors)

Both progressions are in the key of G. The D is the V(5) chord in the G Chord Family, but there is no D7 in this example. That means the 7ths in this example come from outside the key of G. The chords changed to 7ths are the Em (ii) and the Am (iii). This is just a different example of how 7th chords can be used.