Chord Types Triads Triads are made up exclusively from major and minor thirds (in close root position). There are only four possibilities: Chord Type Interval between third and fifth Interval between root and third
Diminished
Minor
Major
Augmented
m3
M3
m3
M3
m3
m3
M3
M3
Seventh Chords There are three possible types of sevenths (major, minor, and seventh), each of which could, in principle, be added to each of the four types of triads. In practice, however, only about half of the possible combinations are used – the ones that naturally occur in the scale. In practice, chords with a minor seventh are substantially more common than others. They can be added to each type of triad. Major sevenths are sometimes added to each type of triad except diminished, but the scale degrees on which they are found rarely use a seventh – especially in earlier music, though it becomes common enough with major and minor chords by the twentieth century. The diminished seventh only occurs on a diminished triad. The augmented triad is a special case. It naturally occurs on the third scale degree of the harmonic minor scale. But, it is almost never used this way. An augmented triad is perfectly symmetrical. Not only are the bottom two intervals major thirds, but the interval between the fifth and the octave of the root is a diminished fourth, which is enharmonically the same thing as another major third. Hence, in some sense, the augmented triad is uninvertible – any one of the notes could be the root. The third of the naturally occurring augmented triad (on ) is , and so we usually treat the augmented chord as though it is a variation of instead of . Hence, although the naturally occurring seventh would be a major seventh (compared to ), the seventh that is more commonly chosen is the minor seventh that belongs to a chord.
III 5
V
III
III
V
Each chord can be named two ways: one compound name, from the name of the triad and the type of seventh, and one simple name. Simple
Diminished Seventh
HalfDiminished Seventh Compound Diminished- Diminisheddiminished minor seventh seventh Seventh Diminished Minor Triad Diminished Diminished
Minor Seventh
n/a
Dominant Seventh
Major Seventh
Minorminor seventh Minor Minor
Minormajor seventh Major Minor
Majorminor seventh Minor Major
Majormajor seventh Major Major
(Dominant seventh augmented) Augmentedminor seventh Minor Augmented
