Seventh Chord Construction | Dominant Seventh Chords (3 of 5)

A Dominant seventh chord is unique in that it consists of the notes of a Major triad but with the addition of an interval of a minor seventh above the root note. This combination of a Major triad and minor seventh interval is what gives the Dominant seventh chord its defining sound.

To get a better idea, let's put together a Dominant seventh chord above the root note C.

CMajorTriad.png

The notes of a C Major triad are C, E and G,

MinorSeventh_CBflat.png

and an interval of a minor seventh above the note C is the note B-flat.

CDominant7.png

By playing the notes of a C Major triad together with the note B-flat we will have constructed a C Dominant seventh chord.

GMajorTriad.png

In that same way, the notes of a G Major triad are G, B, and D,

MinorSeventh_GF.png

and an interval of a minor seventh above the note G is the note F.

GDominant7.png

By adding F to the notes of a G Major triad we will have created a G Dominant seventh chord.

Because of the combination of Major triad and minor seventh interval, the notes of a Dominant seventh chord may not be taken from either a single Major or minor scale. Rather, the scale from which the notes of a Dominant seventh chord may be derived is the Mixolydian mode.

Now, the notes of Mixolydian are very similar to the notes of a Major scale with the exception of a very important flattened seventh scale degree.

Here are the notes of D Mixolydian.

DMixolydianMode.png

If we play the first scale degree, D, together with the third scale degree, F-sharp, the fifth scale degree, A, and the seventh scale degree, C,

DMixolydianMode_D7.png

we will be playing the notes of a D Dominant seventh chord.

DDominant7.png

Similar to Major and minor seventh chords, Dominant seventh chords may also be constructed by following a specific pattern of intervals above a given note: Major third, minor third, minor third.

Dom7_IntervalPattern.png

Let's use this interval pattern to construct a Dominant seventh chord above the note F. An interval of a Major third above the note F is the note A, an interval of a minor third above the note A is the note C, and an interval of a minor third above C is the note E-flat.

F7_IntervalPattern.png

Here we can see that the notes of an F Dominant seventh chord are F, A, C, and E.

FDominant7.png

Use this pattern of intervals to construct a Dominant seventh chord above any given note.