Dominant 7 Chords (V7)
A dominant seventh chord is a four note chord that starts on the fifth note of a scale. It has a feeling of tension that is resolved by the tonic chord (Roman numeral I).
To build a 7th chord, begin with a major triad.
G Major Triad
The 7th of the chord is a minor 7th away from the root.
Ways to find the minor 7th from a given note:
Go down a whole step from the root, then place that note on top.
Lower the 7th note of the root’s (G) major scale by a half step (F# to F).
Add “Fa” (the fourth note of your tonic (C) key’s scale - F) to the V (G) chord.
G to F - Interval of a minor 7th
Add the 7th to the major triad to form the dominant 7 chord.
G7 chord in root position
In solfege, Sol, Ti, Re, Fa are the notes in the V7 chord.