Dominant Seventh Chord

Use the formula 1-3-5-flat 7:

Write the symbol as C7. The plain 7 means a major triad plus minor seventh.

E and B flat form a tritone inside C7.

When C7 resolves to F major, E rises to F and B flat falls to A. Each voice moves by one semitone.

The root C often moves down a fifth or up a fourth to F. These combined motions create a strong dominant-to-tonic cadence.

No. Dominant seventh names a chord structure, while dominant function describes its role.

C7 functions as V7 in F major or F minor. In a C blues, C7 can act as the tonic chord even though its structure is dominant seventh.

Read the following harmony before deciding what the chord is doing.

The diatonic dominant seventh appears on degree 5.

In F major, degree 5 is C. Stack scale tones C-E-G-B flat and you get C7.

In C major, the diatonic dominant is G7: G-B-D-F. It resolves to C through B-C and F-E.

A secondary dominant temporarily treats a diatonic chord as a local tonic.

In C major, A7 contains C sharp outside the key and can resolve to Dm. It is written V7/ii because A7 is the dominant of degree ii.

The temporary leading tone C sharp rises to D. The progression remains in C unless Dm becomes a new sustained tonic.

A blues progression commonly uses dominant-seventh structures on I, IV and V.

In C blues, those chords may be C7, F7 and G7. Their thirds and sevenths combine with blues melody and do not all behave like ordinary diatonic dominants.

Follow the form and style-specific voice leading instead of requiring every seventh chord to resolve by fifth.

C Mixolydian contains C-D-E-F-G-A-B flat and matches the unaltered chord.

C half-whole diminished supplies flat 9, sharp 9, sharp 11 and 13 around C7. C altered supplies common altered tensions and usually supports a strong resolution to F.

Choose a scale from the exact symbol, melody and function. C7 does not require one universal scale.

C7 is C-E-G-B flat.

Cmaj7 raises B flat to B. Cm7 lowers E to E flat.

Compare the guide tones: E-B flat in C7, E-B in Cmaj7 and E-flat-B-flat in Cm7. Those pairs identify the three structures efficiently.

C7 has four bass positions:

The chord remains C7. A slash symbol such as C7/E specifies the bass.

Keep E and B flat because they define quality and voice leading.

The unaltered fifth G can be omitted in a dense ensemble. A bassist may supply C, leaving a pianist to play E-B flat plus extensions.

Avoid crowding root and altered tensions in a low register. Place extensions where their individual lines remain audible.

Build C7, F7 and G7 from the formula.

Play C7-F and sing E-F, then B-flat-A. Repeat G7-C with B-C and F-E.

Finally, hold C7 as a blues tonic and compare its behavior with the same chord resolving to F.