Seventh Chords

Start with a triad and stack one more third above its fifth.

C major is C-E-G. Add B, another third above G, and you get C-E-G-B: Cmaj7.

The name seventh refers to the distance from root to the added note. Count C, D, E, F, G, A, B and you reach seven letter names.

The seventh can be major, minor or diminished. Its quality combines with the triad quality to determine the full chord symbol.

These three chords differ by one or two notes:

Move B in Cmaj7 down one semitone and you get C7. Then move E down one semitone and you get Cm7.

A plain 7 means dominant-seventh structure. The word maj in Cmaj7 describes the seventh, while the absence of m after C leaves the triad major.

Using C as root:

The half-diminished chord Cm7 flat 5 uses a diminished triad plus minor seventh. The fully diminished chord lowers the seventh one more semitone.

B double flat sounds like A on an equal-tempered piano. Its spelling identifies a diminished seventh above C and preserves the chord structure.

No. C7 contains E and B flat, a tritone. In a tonal progression it often resolves to F major: E rises to F and B flat falls to A.

Cmaj7 has B one semitone below the octave C. It can sound settled as a tonic chord and retain close internal color.

Cm7 often functions as a stable tonic sonority in soul, modal music and jazz, or as ii in B-flat major. Its function depends on the key and progression.

Chord type supplies possible voice-leading motions. The key and progression determine which motions listeners expect.

Stack four scale notes in thirds on every degree of C major:

The pattern is maj7, m7, m7, maj7, dominant 7, m7, half-diminished.

Only degree V produces the dominant-seventh structure naturally. Its tritone and root movement by fifth help direct the progression back to I.

Natural minor produces several useful seventh chords, but tonal minor frequently raises degree 7 to create a stronger dominant.

In A minor, E-G sharp-B-D forms E7 and resolves to Am. G sharp is the raised seventh of A harmonic minor.

The raised leading tone also creates G sharp diminished seventh when four thirds are stacked from degree 7. Minor-key harmony therefore moves flexibly between natural and harmonic minor note collections.

A four-note seventh chord has four bass positions:

The pitch classes remain C, E, G and B. The bass changes spacing, voice leading and harmonic weight.

Slash symbols can specify the bass, such as Cmaj7/E. Classical figured bass uses 7, 6/5, 4/3 and 4/2 for the four positions.

Not always. The root identifies the harmonic foundation, the third shows major or minor quality and the seventh distinguishes many chord types.

The fifth is often omitted from an unaltered seventh chord when another instrument supplies the root or the voicing needs space. Altered fifths must remain because they define the chord.

A guitarist, pianist and bassist can divide the notes between them. The chord symbol names their combined harmony; each player can choose a suitable shape or voicing.

Build Cmaj7, C7 and Cm7 by changing one note at a time. Say the moving note before you play it.

Next, build the seven diatonic seventh chords in C major and name their scale degrees.

Finally, play G7-Cmaj7 and follow B to C and F to E. Hearing the individual voices explains the resolution more clearly than memorizing that V goes to I.