The A Dominant 7th chord is a four-note chord made up of A, C♯, E, and G. It is built from a root, major third, perfect fifth, and minor seventh.
Construction
A Dominant 7th = Root + Major 3rd + Perfect 5th + Minor 7th = A · C♯ · E · G
| Note | Interval | Degree |
|---|---|---|
| A | Root | 1 |
| C♯ | Major 3rd | 3 |
| E | Perfect 5th | 5 |
| G | Minor 7th | ♭7 |
A Dominant 7th Inversions
| Position | Notes |
|---|---|
| Root Position | A – C♯ – E – G |
| 1st Inversion | C♯ – E – G – A |
| 2nd Inversion | E – G – A – C♯ |
| 3rd Inversion | G – A – C♯ – E |
Key Signature
A dominant chord points home to the key a fifth below its root: the A Dominant 7th is the V (dominant) of D Major, so the relevant key signature is that key’s — 2 sharps (F♯, C♯). Spelled as a scale, these notes are A Mixolydian.
F♯C♯
Order of sharps
Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.
F♯C♯G♯D♯A♯E♯B♯
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of D Major
These are the triads built on each degree of the D major scale:
How A Dominant 7th functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where A Dominant 7th sits diatonically across the common keys:
- In D major, A Dominant 7th is the V chord — the dominant.
- In B minor, A Dominant 7th is the ♭VII chord — a mediant / color chord.
A Dominant 7th — Frequently Asked Questions
What is the A Dominant 7th chord on piano?
The A Dominant 7th chord contains the notes A – C♯ – E – G. On piano, play these notes together to sound the chord.
What notes are in the A Dominant 7th chord?
The A Dominant 7th chord (A7) contains four notes: A (root), C# (major third), E (perfect fifth), and G (minor seventh). The major triad with a minor seventh creates the bluesy tension and forward drive that defines the dominant 7th sound.
How does A Dominant 7th differ from A Major?
A Major contains three notes: A, C#, E. A Dominant 7th adds a G (minor seventh) on top. That single note transforms a stable, resolved chord into one with strong forward motion — it wants to resolve down a fifth to D Major.
What does 'dominant' mean in music theory?
'Dominant' refers to the fifth scale degree. The dominant 7th chord is built on the fifth note of a key and contains a tritone that creates strong pull toward resolution. A7 is the dominant chord in D Major, one of the most common keys in popular music.
How is A Dominant 7th used in music?
A7 resolves to D Major in a V7–I cadence. It is one of the most used dominant 7th chords in blues, rock, and country music. A7 is also the V7 chord in a blues in D and appears as a secondary dominant (V7/V) in the key of G.
What songs use dominant 7th chords?
Dominant 7th chords are the backbone of blues and early rock: every chord in a standard 12-bar blues is a dominant 7th. Hit the Road Jack (Ray Charles), Ain't Misbehavin' (Fats Waller), and countless jazz standards rely on dominant 7th movement for their harmonic drive.
What is the tritone in A Dominant 7th?
The tritone in A7 is the interval between C# (the third) and G (the seventh) — exactly 6 semitones apart. This unstable interval gives A7 its strong pull toward D. The C# resolves up to D and the G resolves down to F#.