Seventh Chords

G7

It doesn't want to stay there does it?

It leaves you waiting for the other shoe to drop.
It wants to move to a more resolved chord.

The resolved chord would be: C

7th chords are built naturally on the V dominant chord of the major scale, hence the name dom 7th.

By playing alternating scale tones starting with the 5th note of any major scale: 5-7-2-4 of that scale, we naturally build a dom 7th chord.

A dom 7 wnats to resolve to the chord lying a 5th below it.

G7 wants to resolve to a C chord.

But it can resolve just as well to minor.

A dominant chords have this special imeptus, their most traditioanl use is to bring the music back home to its tonic key V7-I.

If one creates a dominant 7th on notes other than the V, this will push the music temporarily to new keys.

This is the reason that a V6 chord will not occure as often as a V7.

The latter is more functional cuz it helps pull the music back to its home tonic key.