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Discussion 3b - Seventh Chords

Class Discussion

TBD

Further Reading

From Open Music Theory

Seventh chords

A four-note chord whose pitch classes can be arranged as thirds is called a seventh chord.

Like with a triad, the pitch classes belonging to a seventh chord occupy adjacent positions (a four-pitch-class clump) on the circle of thirds. The four members of a seventh chord are the root, third, fifth, and seventh.

A seventh chord (A, C, E, G) on the diatonic circle of thirds.

There are five qualities of seventh chords that appear in diatonic music: major seventh, dominant seventh, minor seventh, diminished seventh (also called fully-diminished), and half-diminished seventh. They are comprised of the following intervals above their roots:

  • major seventh: M3, P5, and M7 above the root (or major triad with a major seventh)
  • dominant seventh: M3, P5, and m7 above the root (or major triad with a minor seventh)
  • minor seventh: m3, P5, and m7 above the root (or minor triad with a minor seventh)
  • diminished seventh: m3, d5, and d7 above the root (or diminished triad with a diminished seventh)
  • half-diminished seventh: m3, d5, and m7 above the root (or diminished triad with a minor seventh)

Following are the lead-sheet abbreviations for seventh-chord qualities:

  • major seventh: maj7 or △7 (Gmaj7 or G△7)
  • dominant seventh: 7 (B7)
  • minor seventh: m7 (F♯m7)
  • diminished seventh: dim7 or °7 (Ddim7 or D°7)
  • half-diminished seventh: ⦰7 (A⦰7)