A dominant seventh chord is composed using a root/1st, major 3rd, perfect 5th and minor 7th (or R/1-3-5-♭7) intervals played simultaneously. Generally written as C7, Cdom7 or C7, it is good practice to simply use an uppercase C and a super scripted 7 to represent it in writing (ie: C7).
The dominant seventh chord is built upon the fifth degree of the harmonized major scale (tetrads), and is widely used in all styles of music. Authentic cadence is achieved when the dominant seventh chord is resolved to the tonic chord (for example: G7 to CMA). The tonality of a dominant seventh chord is somewhat dissonant and unresolved when played as the V chord resolving to the I, but is frequently used as the I chord particularly in Funk and Blues styles. Blues players regularly substitute major chords for dominant seventh chords, for example: a I-IV-V progression in the key of G would normally be GMA, CMA and D7, Blues players may change this to G7, C7 and D7.
Dominant seventh chord profile
|Intervals||root/1st, major 3rd, perfect 5th, minor 7th or R/1-3-5-♭7|
|Stability||Somewhat dissonant, unresolved|
|Common names (examples in C)||C7, Cdom7, CDOM7, C7, C(♭7)|
Dominant seventh chord table
|Chord name||Root||Major third||Perfect fifth||Minor seventh|
|A♯7||A♯||C (D)||E♯ (F)||G♯|
|C Dominant seventh chord voicing #2|