Introduction to functional harmony — ii, iii, vi, and vii° chords

The ii chord: the supertonic

The diatonic triad built on scale degree 2, called the ii chord, is a minor predominant chord. It consists of degrees 2, 4, and 6 of the major scale. In the same way that the dominant (V) chord, based a fifth above the tonic, has a tendency to resolve to the tonic; the ii chord, based a fifth above the dominant, has a tendency to resolve to the dominant. Its root note can be found in the dominant chord, and its scale degrees 4 and 6 naturally resolve to the dominant’s degrees 5 and 7.

The vi chord: the submediant

The diatonic triad built on scale degree 6, called the vi chord, is a minor chord including scale degrees 6, 1, and 3 of the major scale. The vi chord shares two notes with both the tonic (I) and subdominant (IV) chords. It is sometimes classified as a substitute for, or an extension of, the tonic; however, it is most commonly considered to be a predominant chord. Like the V and ii chords, it has a tendency to resolve down a fifth, in this case to the predominant ii chord.

The iii chord: the mediant

The diatonic triad built on scale degree 3, called the iii chord, consists of major scale degrees 3, 5, and 7. Its function is somewhat ambiguous, as it shares two notes with both the tonic (I) and dominant (V) chords. Because of this, it is sometimes considered to be a substitution for both tonic and dominant chords. It can also be thought of as a “weak” predominant, as it resolves to other predominant chords, especially down a fifth to the vi chord.

The vii° chord: the leading tone

The triad built on scale degree 7, called the vii° chord and consisting of scale degrees 7, 2, and 4, is the only diminished triad which naturally occurs in the major scale. Its root, the leading tone, has a strong tendency to resolve up to the tonic note; and its scale degrees 2 and 4 naturally pull to the tonic chord’s 1, 3, and 5. Because of its role of resolving to the tonic, it is considered to be a dominant chord.