Secundal, tertian, and quartal chords[edit]

See also: Secundal, Tertian, Quartal and quintal harmony and Mixed-interval chord

Chord Component intervals

Secundal 2nd's : major 2nd, minor 2nd

Tertian 3rd's : major 3rd, minor 3rd

Quartal 4th's : perfect 4th, augmented 4th

Quintal 5th's

Quartal chord: C-F-B chord[29]   Play (help·info).

Many chords are a sequence of ascending notes separated by intervals of roughly the same

size. Chords can be classified into different categories by this size:

Tertian chords  can be decomposed into a series of (major or minor) thirds. For

example, the C major triad (C-E-G) is defined by a sequence of two intervals, the first (C-

E) being a major third and the second (E-G) being a minor third. Most common chords

are tertian.

Secundal chords  can be decomposed into a series of (major or minor) seconds. For

example, the chord C-D-E♭ is a series of seconds, containing a major second (C-D) and

a minor second (D-E♭).

Quartal chords  can be decomposed into a series of (perfect or augmented) fourths.

Quartal harmony normally works with a combination of perfect and augmented fourths.

Diminished fourths are enharmonically equivalent to major thirds, so they are uncommon.[30] For example, the chord C-F-B is a series of fourths, containing a perfect fourth (C-F) and

an augmented fourth/tritone (F-B).

These terms can become ambiguous when dealing with non-diatonic scales, such as

the pentatonic or chromatic scales. The use of accidentals can also complicate the

terminology. For example, the chord B♯-E-A♭ appears to be a series of diminished fourths (B♯-

E and E-A♭) but is enharmonically equivalent to (and sonically indistinguishable from) the

chord C-E-G♯, which is a series of major thirds (C-E and E-G♯).

Harmonic Content[edit]

The notes of a chord form intervals with each of the other notes of the chord in combination. A

3-note chord has 3 of these harmonic intervals, a 4-note chord has 6, a 5-note chord has 10, a

6-note chord has 15.[31] The absence, presence, and placement of certain key intervals plays a

large part in the sound of the chord, and sometimes of the selection of the chord that follows.

A chord containing tritones is called tritonic; one without tritones is atritonic. Harmonic tritones

are an important part of Dominant seventh chords, giving their sound a characteristic tension,

and making the tritone interval likely to move in certain stereotypical ways to the following

chord.[32]

A chord containing semitones, whether appearing as Minor seconds or Major sevenths, is

called hemitonic; one without semitones is anhemitonic. Harmonic semitones are an important

part of Major seventh chords, giving their sound a characteristic high tension, and making the

harmonic semitone likely to move in certain stereotypical ways to the following chord.[33] A chord

containing Major sevenths but no Minor seconds is much less harsh in sound than one

containing Minor seconds as well.

Other chords of interest might include the