We recommend knowing first
The problem it solves
To close a phrase forcefully you need a chord that generates tension directed toward the tonic. The dominant seventh is exactly that: the chord that pushes and asks to resolve.
Detailed theory
Key idea
A dominant 7 chord is a major triad (1-3-5) with the minor seventh added (b7): the formula is 1-3-5-b7.
The third and the minor seventh form a tritone, the interval that gives the chord its characteristic tension and makes it resolve to the tonic (V7→I).
Understand it
Start from a major triad and add the minor seventh, counted from the root. In G it is G-B-D-F. The F is the minor seventh: it sits ten semitones above the G, that is, a tone below the octave (not a semitone, as in the maj7).
The heart of the chord is the tritone formed by the third (B) and the seventh (F): they are exactly six semitones apart. This interval is unstable by nature and is what gives the dominant all its push: the ear asks for it to resolve.
When G7 resolves to C (V7→I), the two notes of the tritone move by step toward stable notes: the B (leading tone) rises to C and the F falls to E. This double motion is what makes the arrival at the tonic feel inevitable, and it is the basis of tonal harmony, the blues and jazz.
An analogy: the dominant seventh is like a stretched spring. The tritone is the stored tension; when you let the spring go, it snaps back to its place of rest (the tonic). As long as it stays stretched, it asks to resolve.
maj7 vs dominant 7: both start from a major triad and add a seventh, but the kind of seventh changes everything. The maj7 has a major seventh (stable, full and lush, like Cmaj7 = C-E-G-B, where the seventh sits a semitone below the octave and rests). The dominant 7 has a minor seventh (tense, wanting to resolve, like C7 = C-E-G-Bb, or G7→C): the minor seventh forms a tritone with the third and pushes toward the tonic.
Interval distance
B–F tritone: the engine of the dominant. Exactly six semitones between the third and the seventh of G7. It is the unstable interval that asks for resolution.
How to recognise it
How it's written
It is written with a lone 7 over the root of a major triad: G7, C7, D7. On the staff you see four notes stacked in thirds; the top one is the minor seventh, a tone below the octave of the root. In degrees it is V7.
How it feels
It sounds full but restless: you feel a tension that wants to go somewhere else. Play G-B-D-F and then C major; you will hear how the first chord pushes and the second answers and closes.
Common mistake
Confusing the dominant 7 (minor seventh, 1-3-5-b7, with a tritone) with the maj7 (major seventh, 1-3-5-7, with no tritone and stable).
Not hearing the tritone between third and seventh: it is what defines the dominant and what makes it resolve; without it the chord would not push.
Try it
On the keyboard, play just the B and the F of G7 together: that restless pair is the tritone, the engine of the chord.
Play G7 and resolve to C major (V7→I): follow the B rising to C and the F falling to E.
On the instrument
Staff & keyboard
Loading audio…
G7 = G-B-D-F. The major triad (G, B, D) plus the minor seventh (F). The third (B) and the seventh (F) form the tritone that gives the chord its tension. Tap each note.
Where it's used
- Closing a phrase forcefully
- Using V7 → I to create the most conclusive cadence: the tritone tension resolves into repose at the tonic.
- A blues and jazz sound
- Using dominant 7 chords as the basic colour of the blues (where they can even appear over the tonic) and as the engine of the jazz ii-V-I.
Examples
Chord progression
Loading audio…
V7 → I in C major: G7 resolves to C. The tritone tension unwinds as the B rises to C and the F falls to E. It is the most conclusive cadence.
Prepares you for
Exercises
Play dominant 7 chords
Play the dominant 7 chord shown, on any root.
Complete 6 attempts · 70% accuracy to pass
Mini test
Check that you've got it.
0/6 answeredQuestion 1/6
How is a dominant seventh chord built?