The C♯ Dominant 7th chord is a four-note chord made up of C♯, E♯, G♯, and B. It is built from a root, major third, perfect fifth, and minor seventh.
Construction
| Note | Interval | Degree |
|---|---|---|
| C♯ | Root | 1 |
| E♯ | Major 3rd | 3 |
| G♯ | Perfect 5th | 5 |
| B | Minor 7th | ♭7 |
C♯ Dominant 7th Inversions
| Position | Notes |
|---|---|
| Root Position | C♯ – E♯ – G♯ – B |
| 1st Inversion | E♯ – G♯ – B – C♯ |
| 2nd Inversion | G♯ – B – C♯ – E♯ |
| 3rd Inversion | B – C♯ – E♯ – G♯ |
Key Signature
A dominant chord points home to the key a fifth below its root: the C♯ Dominant 7th is the V (dominant) of F# Major, so the relevant key signature is that key’s — 6 sharps (F♯, C♯, G♯, D♯, A♯, E♯). Spelled as a scale, these notes are C# Mixolydian.
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.
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of F♯ Major
These are the triads built on each degree of the F♯ major scale:
How C♯ 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 C♯ Dominant 7th sits diatonically across the common keys:
- In F♯ major, C♯ Dominant 7th is the V chord — the dominant.
- In D♯ minor, C♯ Dominant 7th is the ♭VII chord — a mediant / color chord.