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The dominant seventh chord is a fundamental element in music theory, especially within Western tonal music. It creates tension that seeks resolution, making it essential for composers and musicians to understand its structure and formula.
What Is a Dominant Seventh Chord?
A dominant seventh chord is built on the fifth degree of a major or minor scale. It combines a major triad with a minor seventh interval from the root, producing a rich, dissonant sound that naturally resolves to the tonic chord.
Formula of a Dominant Seventh Chord
The general formula for a dominant seventh chord is:
- Root
- Major third
- Perfect fifth
- Minor seventh
In terms of intervals from the root, it is: 1, 3, 5, ♭7.
Examples in C7 and G7
Let’s examine how this formula applies to the chords C7 and G7.
C7 Chord
The C7 chord consists of the following notes:
- C (Root)
- E (Major third)
- G (Perfect fifth)
- B♭ (Minor seventh)
Using the formula, C7 is built from the notes 1, 3, 5, ♭7.
G7 Chord
The G7 chord includes these notes:
- G (Root)
- B (Major third)
- D (Perfect fifth)
- F (Minor seventh)
Similarly, G7 follows the formula with notes 1, 3, 5, ♭7.
Importance of the Dominant Seventh
The dominant seventh chord plays a crucial role in establishing tonality. Its dissonance creates a strong desire for resolution, typically resolving to the tonic chord, which provides a sense of closure and stability.
Conclusion
Understanding the formula of the dominant seventh chord is essential for both performers and composers. Recognizing the structure in examples like C7 and G7 helps in mastering harmonic progressions and creating expressive musical phrases.