C sharp Dominant Seventh Chord (C♯7)

1Composition: what it contains

C♯ – E♯ – G♯ – B

Symbol

C♯7

Also written

C♯7, C♯dom7

Formula

1 3 5 ♭7

Same sound as

D♭7

2Appearance: diagrams and sound

On the guitar

On the ukulele

On the piano

On the staff

On bass and as an arpeggio

3Indications: what it is used for

The V7 chord of a major or minor key, resolving to I or i: the most important cadence in tonal music. In blues, every chord (I7, IV7, V7) is a dominant seventh, used as a stable colour rather than tension. Secondary dominants (V7/ii, V7/V...) create chromatic movement, and tritone substitution replaces a V7 with the dominant seventh a tritone away. It is fundamental in jazz, blues, funk, rock and roll, gospel and classical music.

4Dosage: how to practise it

On guitar, learn the open shapes, the barre shapes rooted on the sixth and fifth strings, and shell voicings (root, third, seventh). On piano, play the chord in all inversions, then practise V7–I with the third resolving up a half step and the seventh resolving down. Play a twelve-bar blues with dominant sevenths at 80–120 BPM with a shuffle feel. Arpeggiate 1-3-5-♭7 on bass. Practise ii–V–I loops for ten minutes daily.

5Warnings and common mistakes

The symbol '7' alone means a dominant seventh (flat seventh), not a major seventh: this is the most common chord-symbol mistake. Do not confuse it with maj7 or m7. In voicings, omit the fifth rather than the third or seventh, which define the chord. The tritone between third and seventh should resolve properly in classical writing; parallel dominants are fine in blues. Avoid playing the root note of the next chord on top in a way that hides the resolution.

6Interactions with chords, scales and keys

Inversions

• Inversion 1 · C♯7/E♯ · E♯ – G♯ – B – C♯ Play
• Inversion 2 · C♯7/G♯ · G♯ – B – C♯ – E♯ Play
• Inversion 3 · C♯7/B · B – C♯ – E♯ – G♯ Play

Scales to play over C♯7

• D flat Mixolydian Mode
• C sharp Half-Whole Diminished Scale
• C sharp Phrygian Dominant Scale
• D flat Lydian Dominant Scale
• D flat Bebop Dominant Scale

Where it appears (keys and Roman numerals)

• V7 – Key of F sharp Major
• V7 – Key of G flat Major
• V7 – Key of F sharp Minor
• VII7 – Key of D sharp Minor
• VII7 – Key of E flat Minor

7Other presentations available

The same chord from every note

C7 D7 E♭7 E7 F7 F♯7 G7 A♭7 A7 B♭7 B7

Other chords on C♯

C♯ C♯m C♯dim C♯aug C♯sus2 C♯sus4 C♯5 C♯6 C♯m6 C♯maj7 C♯m7 C♯m7♭5 C♯dim7 C♯m(maj7) C♯7sus4 C♯add9 C♯m(add9) C♯6/9 C♯9 C♯maj9 C♯m9 C♯11 C♯m11 C♯13 C♯7♭9 C♯7♯9 C♯7♯5 C♯7♭5