Predominant Seventh Chords

Adding a seventh to a predominant triad produces a chord with even stronger voice-leading pull toward the dominant. The two most important predominant seventh chords are ii⁷ (supertonic seventh, a minor seventh chord in major) and IV⁷ (subdominant seventh). Both contain 4̂ (fa) and 6̂ (la) — the same pitches that define predominant function — plus the additional dissonance of the seventh, which must resolve by step. Their added urgency makes phrase endings feel more inevitable.

In major keys, ii⁷ (2̂–4̂–6̂–1̂) is a minor seventh chord. Its seventh (1̂, do) is prepared as a chord tone of the tonic and resolves down by step to 7̂ (ti) in the dominant. The chord commonly appears in root position or first inversion (ii⁶₅), the latter placing 4̂ in the bass for a smooth stepwise descent to 5̂ (sol). In minor keys, the supertonic triad is diminished (iiº), and adding a minor seventh produces iiø⁷ (half-diminished seventh) — the same quality as the leading-tone seventh in major, but now serving as a powerful minor-key predominant.

IV⁷ (subdominant seventh) places 4̂ in the bass with 6̂ and 1̂ above, plus the seventh (3̂, mi) — a pitch shared with the tonic. This overlap with tonic content gives IV⁷ a slightly less urgent quality than ii⁷, but it nonetheless resolves effectively to V when the seventh descends by step. In practice, ii⁷ and ii⁶₅ are by far the more common predominant seventh chords in Classical voice-leading style; IV⁷ appears more often in popular and folk contexts. Recognizing predominant sevenths by their scale-degree content (especially the presence of 4̂ and 6̂ together) makes them easy to identify regardless of inversion.