B Dominant Seventh Chord (B7)

1Composition: what it contains

B – D♯ – F♯ – A

Symbol

B7

Also written

B7, Bdom7

Formula

1 3 5 ♭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 · B7/D♯ · D♯ – F♯ – A – B Play
• Inversion 2 · B7/F♯ · F♯ – A – B – D♯ Play
• Inversion 3 · B7/A · A – B – D♯ – F♯ Play

Scales to play over B7

• B Mixolydian Mode
• B Half-Whole Diminished Scale
• B Phrygian Dominant Scale
• B Lydian Dominant Scale
• B Bebop Dominant Scale

Where it appears (keys and Roman numerals)

• V7 – Key of E Major
• V7 – Key of E Minor
• VII7 – Key of C sharp Minor

7Other presentations available

The same chord from every note

C7 C♯7 D7 E♭7 E7 F7 F♯7 G7 A♭7 A7 B♭7

Other chords on B

B Bm Bdim Baug Bsus2 Bsus4 B5 B6 Bm6 Bmaj7 Bm7 Bm7♭5 Bdim7 Bm(maj7) B7sus4 Badd9 Bm(add9) B6/9 B9 Bmaj9 Bm9 B11 Bm11 B13 B7♭9 B7♯9 B7♯5 B7♭5