What Makes a Chord Dominant in Music?
A chord is considered dominant because its root note is the fifth degree of a musical scale, and it carries a strong harmonic function that creates tension, compelling a resolution back to the tonic, or home key.
The Foundation of Dominance
The essence of a dominant chord lies in its direct relationship to the tonic of a key. In any diatonic scale—be it major or minor—the dominant is specifically identified as the fifth tone or degree. For example, in the key of C, the note G is the dominant degree.
Once this fifth degree is established, a chord is built upon it. This typically involves stacking notes in thirds above the root. The most fundamental form is the dominant triad, which consists of the root, its major third, and its perfect fifth. In the key of C, the dominant triad is formed by the notes G–B–D.
Characteristic Features of Dominant Chords
- Tension and Resolution: Dominant chords inherently create a sense of harmonic tension. This tension arises primarily from the presence of the leading tone (the major third of the dominant chord, which is the seventh degree of the scale) that strongly pulls towards the tonic note. For instance, in a G major dominant chord within the key of C, the note B (the third of G) is the leading tone, pulling directly to C.
- The Dominant Seventh Chord: While a simple dominant triad is functional, the most characteristic and potent form is the dominant seventh chord. This is a major triad with an added minor seventh above the root (e.g., G-B-D-F in the key of C). The tritone interval created by the third and seventh of this chord (B and F in G7) significantly amplifies the tension and strengthens its desire to resolve to the tonic.
- Harmonic Progression: Dominant chords are central to one of the most fundamental chord progressions in Western music: the V-I progression (dominant to tonic). This progression provides a strong sense of closure and stability, making it a cornerstone of musical structure.
Examples of Dominant Chords Across Keys
Understanding the dominant degree helps identify the dominant chord in any given key:
| Key | Tonic Note | Dominant Degree (5th) | Dominant Triad (V) | Dominant Seventh Chord (V7) |
|---|---|---|---|---|
| C Major | C | G | G-B-D | G-B-D-F |
| G Major | G | D | D-F#-A | D-F#-A-C |
| D Major | D | A | A-C#-E | A-C#-E-G |
| A Major | A | E | E-G#-B | E-G#-B-D |
| F Major | F | C | C-E-G | C-E-G-Bb |
In summary, a chord is made dominant by its position as the fifth degree of a scale, its inherent harmonic tension, and its powerful tendency to resolve to the tonic, shaping the melodic and harmonic direction of music.
