Elements of Composition: Chord Construction - Triads and Seventh Chord Formulas

Hi guys,

Last time we looked at where chords come from and how to harmonize a scale. This time we will look at Chord Quality.
Chord quality is fundamentally determined by it's Triad. The Triad consists of the root note of the chord, along with it's 3rd and 5th intervals. The Triad tells us whether the chord quality is major, minor, augmented or diminished. The chord quality can be further defined by adding the 7th interval, such as major 7, dominant 7, half diminished and fully diminished.

Let's look at the difference between a Major Triad and a Minor Triad.

C Major Triad = C E G = Root, 3, 5
C Minor Triad = C Eb G = Root, b3, 5

We can see that the 3rd interval of the minor triad has been flatted. This is our formula for a minor triad. Here are the triad formulas :

Major = Root, 3, 5
Minor = Root, b3, 5
Augmented = Root, 3, #5
Diminished = Root, b3, b5

Here are the 7th chord formulas :

Major 7 = Root, 3, 5, 7
Minor 7 = Root, b3, 5, b7
Dominant 7 = Root, 3, 5, b7
Minor 7, b5 (a.k.a. Half Diminished) = Root, b3, b5, b7
Diminished = Root, b3, b5, bb7
Augmented Dominant = Root, 3, #5, b7
Minor Major 7 = Root, b3, 5, 7

Remember this series of thirds and you will always know the chord tones, be they flatted or sharped:

C E G B D F A C E

This attachment shows the formulas with their chord symbols.

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