The dominant seventh
Add a minor seventh to a major triad, build the chord on the fifth degree and hear its pull to the tonic.
Four notes
A seventh chord has four notes stacked in thirds. The outer notes form a seventh, hence the name.
The dominant seventh chord is a major triad with a minor third on top (from the root to the top note is a minor seventh). It is built on degree V of major and harmonic minor, so it is called the dominant seventh (V7).
A G major triad and the dominant seventh on G4
Practice: Build dominant sevenths
Practice: Recognise the chord
The pull to the tonic
A V7 holds two unstable notes that form a tritone: degree VII (the leading note) and degree IV (the seventh of the chord). That is why it demands resolution so insistently:
- the leading note rises a semitone to the tonic;
- the seventh falls a step to the third of the tonic;
- the fifth falls to the tonic, and the root leaps to the tonic.
Finding the tonic from a V7 is easy: it lies a fifth below the root (or a fourth above).
The V7 of C major (G – F – B – D) resolves to the tonic
G major: the V7 on D and the tonic triad
To build a V7 in a key quickly, take degree V and stack three thirds from the notes of the scale. In minor, remember to raise degree VII: the dominant is major there too.