Basic chords consist of just three notes, arranged in thirds, called a triad. The most common triads are constructed from notes plucked from the underlying scale, each note two steps (tones) above the previous note. Within a specific chord, the first note is called the root—even if the chord isn’t formed from the root of the scale. The other notes of the chord are named relative to the first note, typically being the third and the fifth above the chord’s root.
An Easy Way to Remember Triads. In music theory, it is vital to be able to recognize and construct triads instantly and to relate them to major and minor keys. In this connection it helps to remember that only seven combinations of letter names form the intervals of a 5th and a 3rd; only these seven groups, therefore, form triads. They are:
The whole mass of major and minor triads may be grouped into three sets of two triads each:a) The tonic group viz: the triads on the 1st and 6th degrees.
b) The dominant group viz: the triads on the 5th and 3rd degrees and
c) The subdominant group viz: the triads on the 4th and 2nd degrees.
In marked contrast to the other triads stands the diminished triad on the 7th degree, because of its dissonant character.
Type of chords
In most cases, the type of chord is determined by the middle note — the third (or “sweet note”). When the interval between the first note and the second note is a major third— two whole steps—you have a major chord. When the interval between the first note and the second note is a minor third—three half steps—you have a minor chord. Called common triads, these account for six of the seven possible triads in the major scale and its corresponding relative minor. These six have a special relationship because there are three major chords and three minor chords in the scale. The seven-toned scale thus offers a balance between major and minor influences. What swings it in favor of the major or minor influence is emphasis. Then there’s the augmented triads that are built up from two major thirds and diminished triad which most often acts as a substitute for the dominant or as an incomplete dominant seventh chord.
Considering the intervallic relationship chords can be:
- Major: chords with intervals of a major 3rd from the root and a perfect 5th from the root to the top note (4 plus 3 semitones). They are happy, simple, honest, bold.
- Minor: chords with intervals of a minor 3rd from the root and a perfect 5th from the root to the top note (3 plus 4 semitones). They are sad, serious.
- Diminished: a chord with an interval of a minor 3rd and diminished 5th from the rook (3 plus 3 semitones). They are dark, strained, complex.
- Augmented triad: a chord with an interval of a major 3rd and an augmented 5th from the root (4 plus 4 semitones). They are anticipatory, full of movement.
Considering the entire group of triads the following observations may be made:
- The major triads are: I, IV, V in the major mode; V, VI in the minor mode.
- The minor triads are: II, III, VI in the major mode; I, IV in the minor mode.
- The diminished triads are: VII in the major mode; VII, II in the minor mode.
- There is but one augmented triad-III in the minor mode.
Or, from the point of view of the scale degrees:
- I is a major triad in the major mode, minor in the minor mode.
- II is a minor triad in the major mode, diminished in the minor mode.
- III is a minor triad in the major mode, augmented in the minor mode.
- IV is a major triad in the major mode, minor in the minor mode.
- V is a major triad in both modes.
- VI is a minor triad in the major mode, major in the minor mode.
- VII is a diminished triad in both modes.
There is one more type of chord. It is a very common chord in contemporary music, and it doesn’t fit the normal pattern of stacked thirds. It is the “suspended 4th” chord. The chord symbol used is sus4. A suspended fourth chord (sus4) is a triad in which the 4th degree replaces the 3rd degree.