Acchordion

A Brief Intro to Seventh Chords

Seventh chords are the foundation of jazz and are ubiquitous in pop music. Knowing seventh chords will help you learn new songs more easily, improvise, and even write your own songs. Acchordion helps you learn seven types of chords in each key. Of these seven chord families, four are diatonic and three are non-diatonic.

Diatonic chords are chords made up of only notes that are present in a given key. Each major scale has the following diatonic chords:

I^maj7, ii^m7, iii^m7, IV^maj7, V⁷, vi^m7, vii^min7♭5

In F major, these chords are F^maj7, G^m7, A^m7, B♭^maj7, C⁷, D^m7, and E^min7♭5. In G major, these chords are G^maj7, A^m7, B^m7, C^maj7, D⁷, E^m7, and F♯^min7♭5.

Minor scales also use these chord families, but with a variety of orders and configurations. The simplest minor scale mode is the natural minor scale mode, which uses these chords:

i^m7, ii^min7♭5, III^maj7, iv^m7, v^m7, VI^maj7, VII⁷

In A minor, these chords are A^m7, B^min7♭5, C^maj7, D^m7, E^m7, F^maj7, and G⁷.

As you can see, both the major and natural minor scales use the same 4 types of chord: major 7, minor 7, dominant 7, and minor 7 flat 5.

Non-diatonic chords are chords that include notes that are borrowed from outside the key. These chords are used in the harmonic minor and melodic minor scale modes and sometimes substituted for diatonic chords to add a different color or feel to a harmony. Acchordion includes the following non-diatonic chords: diminished 7, minor-major 7, and suspended dominant 7.

You can determine which notes are in each chord by using the formulae in the table below:

Chord Family	Third Quality	Semitones between Root and Third	Fifth Quality	Semitones between Root and Fifth	Seventh Quality	Semitones between Root and Seventh
Major 7	major	4	perfect	7	major	11
Minor 7	minor	3	perfect	7	minor	10
Dominant 7	major	4	perfect	7	minor	10
Minor 7 Flat 5 (Half-Diminished)	minor	3	diminished	6	minor	10
Diminished 7	minor	3	diminished	6	diminished	9
Suspended Dominant 7	perfect fourth	5	perfect	7	minor	10
Minor-Major 7	minor	3	perfect	7	major	11