Seventh Chords and How They Resolve in Tonal Harmony
The chordal seventh falls, the leading tone rises, and the tritone at the centre of V7 resolves by step. What each diatonic seventh chord is for.
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Adding a seventh to a triad changes what the chord is for. A triad can sit still; a seventh chord cannot, because the added note is a dissonance with a destination. That single fact explains the behaviour of every diatonic seventh chord in tonal music, including the ones that sound gentle.
The diatonic seventh chords
Stack one more third on each triad of a key and you get the full set.
| In major (C) | Notes | Quality | Usual job |
|---|---|---|---|
| Imaj7 | C E G B | major seventh | tonic colour, rarely a resting point |
| ii7 | D F A C | minor seventh | the standard predominant |
| iii7 | E G B D | minor seventh | weak tonic substitute, passing |
| IVmaj7 | F A C E | major seventh | predominant with a softer edge than V7 expects |
| V7 | G B D F | dominant seventh | the dominant, the strongest pull home |
| vi7 | A C E G | minor seventh | tonic substitute, often leading to ii |
| viiø7 | B D F A | half-diminished seventh | dominant function without the root |
| In minor (A) | Notes | Quality | Usual job |
|---|---|---|---|
| i7 | A C E G | minor seventh | tonic colour |
| iiø7 | B D F A | half-diminished seventh | predominant |
| III+maj7 | C E G♯ B | augmented major seventh | tonic area when the leading tone is in use |
| iv7 | D F A C | minor seventh | predominant, heavier than in major |
| V7 | E G♯ B D | dominant seventh | the dominant in minor |
| VImaj7 | F A C E | major seventh | tonic substitute |
| vii°7 | G♯ B D F | fully diminished seventh | dominant function without a root |
Minor is messier because the sixth and seventh scale degrees are flexible. The A minor key uses G♯ when the dominant needs a leading tone and G when the music leans toward the relative major, so a chord like III appears in two forms, C–E–G and C–E–G♯, and the second one takes a major seventh above it.
Why the seventh has to fall
The seventh of a chord is dissonant against the bass: in a root-position seventh chord it sounds a seventh above the root, which is a second below its octave. Dissonances of that kind resolve by step in the direction the interval leans, and a note that leans against the bass resolves downwards. The chordal seventh therefore falls by step into the third of whatever chord comes next, and composers arrange the next chord so that this resolution is already a chord tone.
That is why the seventh is a compositional convenience rather than an obstacle. Because it must move, it guarantees that the next chord’s third is occupied by a real voice, and because it moves down by step, the motion is smooth. Chains of seventh chords with roots falling by fifth are the clearest result: every seventh resolves into the third of the following chord, and the whole sequence leads somewhere without any chord being static.
E minor seven, A minor seven, D minor seven, G seven, C. The bass falls by fifth at every step and each seventh sinks one degree into the next chord’s third.
The tritone in the dominant seventh
The dominant seventh contains both tendency tones of the key, scale degree 4 and the leading tone, and they form a tritone at the centre of the chord. Scale degree 4 falls to 3, the leading tone rises to 1, and the two voices move in contrary motion into the third of the tonic triad.
Whether that tritone appears as a diminished fifth or an augmented fourth depends on the inversion, and the difference matters to a singer reading intervals rather than a theorist reading a symbol. When the leading tone is the lower of the two notes, as in root position and in first inversion, the interval is a diminished fifth. When the seventh is the lower note, as in second and third inversion, it is an augmented fourth. The resolution is the same either way:
- root position V7 resolves to I, with the tritone closing into the third of the tonic
- first inversion V6/5 resolves to I, with the leading tone in the bass rising to the tonic
- second inversion V4/3 resolves to I, with the tritone opening outward
- third inversion V4/2 resolves to I6, because the bass is the seventh and it must fall
That is a third-inversion dominant seventh resolving to a first-inversion tonic. The bass note is the seventh of the chord, so the bass itself makes the stepwise descent from scale degree 4 to 3.
Two rules govern the tritone when it sits between the bass and an upper voice. A diminished fifth above the bass must resolve inward to a third; an augmented fourth above the bass must resolve outward to a sixth. Get that backwards and the interval will still look resolvable on paper while the voices collide in performance.
Incomplete dominants and complete tonics
The dominant seventh has four notes and the tonic triad has three, so one of them usually gives something up. In a strong cadence where the soprano takes the leading tone, the dominant seventh often appears without its fifth, the root doubled in its place. That version resolves to a complete tonic triad with its fifth present.
The alternative is a complete dominant seventh resolving to a tonic with a doubled third and no fifth. Both solutions work, and both avoid the same trap: a seventh chord whose fifth is doubled or whose seventh is doubled will produce parallel octaves or a collision at the resolution, because two voices cannot both resolve the same obligation in the same direction without moving in parallel.
This is also the answer to a question beginners ask about final chords. A tonic seventh chord at the end of a tonal phrase sounds open, because its seventh still has somewhere to go. The stable ending is the triad, not Imaj7.
The other sevenths and their destinations
Every diatonic seventh chord has a habitual next chord, and the pattern is always the same: the seventh resolves, and the destination is chosen so that the resolution is consonant.
- ii7 goes to V, and its seventh is scale degree 1 falling to the leading tone, which is the third of the dominant
- viiø7 and vii°7 go to I, with scale degree 6 in the seventh falling to scale degree 5
- IVmaj7 goes to V, with scale degree 3 falling to the fifth of the dominant
- vi7 usually goes to ii or IV, with scale degree 5 falling to the third of the new chord
- Imaj7 goes to IV, with the leading tone falling to the third of the subdominant
None of these are fixed rules of harmony; they are consequences of the resolution. Any chord that contains the note the seventh is moving to will work, which is why hearing the seventh resolve is a more reliable guide to what comes next than memorising a chart.
Dominant-function chords keep their obligations even when they resolve somewhere unexpected. In a deceptive resolution the dominant seventh moves to vi instead of I, and both tendency tones still do their job: the seventh falls to the fifth of vi and the leading tone rises to its third. The surprise lives entirely in the bass.
Where seventh chords go wrong
Four errors account for most of them.
Doubling the seventh. Two voices on the same dissonant note must both fall, and two voices falling the same distance create parallel motion, usually parallel octaves into the next chord. The seventh is never doubled.
Leaving the seventh unresolved. It can move to another chord tone of the next chord only if that tone lies a step below, which is rare. Otherwise the dissonance hangs in the air and the progression sounds unfinished.
Treating inversions as interchangeable. V4/2 in particular has a specific destination, the first-inversion tonic, because its bass is the seventh. Used elsewhere it produces a bass line that contradicts its own harmony.
Forgetting that a diminished fifth and an augmented fourth need opposite treatment. One resolves inward, the other outward, and the two differ by a single inversion.
Working with them
Try a four-chord exercise in C major: ii7, V7, Imaj7, IVmaj7. Play it, then sing the note that changes at each step. The seventh of ii7 becomes the third of V7; the seventh of V7 resolves into the tonic and the leading tone arrives with it; the new seventh on the tonic falls again into the subdominant. Once that chain of descending steps is audible rather than theoretical, seventh chords stop being chords with extra notes and start being chords with directions. The virtual piano is enough to check any of these progressions by ear, and secondary dominants covers what happens when the same mechanism is aimed at a tonic that is not the main one.
Questions
What is a dominant seventh chord and where does it resolve?
The dominant seventh is V7, built on the fifth degree. In C major it is G, B, D and F. Its seventh, F, falls by step to E, and the leading tone B rises to C, so the chord normally resolves to the tonic.
Why does the seventh in a seventh chord have to fall?
The seventh sounds dissonant against the bass, and dissonances resolve by step in the direction they lean, which is downward for the seventh. The seventh therefore falls into the third of the next chord, and composers arrange that chord so the resolution is already a chord tone.
Why should a piece end on a triad rather than a seventh chord?
A tonic seventh chord sounds open at the end of a phrase because its seventh still has somewhere to go. The stable close is the tonic triad. A triad can sit still, while a seventh chord carries a direction that asks to be resolved.
