Theory
A minor triad includes three notes and these can be referred to as the root, minor third and perfect fifth. It can also be referred to the first, the third and the fifth notes in the related scale.
We can compare the A Minor Scale with the A Minor chord:
A Minor scale: A – B – C – D – E – F – G
A Minor chord: A – C – E
The difference between the Minor and Major chord is the second note. The minor third changes to a major third.
We can compare the C Minor with the C Major:
C Minor chord: C – Eb – G
C Major chord: C – E – G
Formula and steps
A good way to minimize the memorizing is to learn the formulas. The formula for a triad minor chord is 1 - b3 - 5, which refers to the minor scale degrees.
You could also learn by steps. From the 1st note go three half steps to the right to the 2nd note, and from the 2nd note go four steps to the right to the 3rd note.
Make use of
How and when to use minor triads? These are among the most common of all chords and used in various music genres and situations. Minor chords are normally used together with major chords in different combinations.
Chord sequences that shows how major chords can be utilized:
1. Am Em F G
2. Em C D G
3. Dm G C
In Roman numerals*:
1. i v VI VII
2. i VI VII III
3. i IV VII
* Roman numerals describe chord intervals that can be used the same way in all keys. See a table over minor keys including Roman numerals.
Other minor chords
As mentioned earlier, there are more groups of minor chords. The most common among these are Minor 7th.
Comparing the A Minor Scale with the A Minor 7th chord:
A Minor scale: A – B – C – D – E – F – G
A Minor 7 chord: A – C – E – G
With an alternative chord name that is seldom used Cm7 could be written C-7.
The Minor 6th chord is consequently built by adding a sixth note. This is actually the same note that is added to a Major 6th (this chord is sometimes referred to as Minor Major 6th) and that means that the Minor 6 chord doesn't incorporate with its relative scale:
Comparing the A Minor Scale with the A Minor 6th chord:
A Minor scale: A – B – C – D – E – F – G
A Minor 6 chord: A – C – E – F#
Because of this odd feature, the Minor 6th are often treated as an add6 chord. Regardless of names, the important part is that it is a minor triad with an added major third.
The next chord family is called Minor ninth (m9). This chord is built by adding a major third to a minor seventh chord.
Comparing the A Minor Scale with the A Minor 9th chord:
A Minor scale: A – B – C – D – E – F – G
A Minor 9 chord: A – C – E – G – B
With an alternative chord name that is seldom used Cm9 could be written C-9.
The next group is the Minor eleventh (m11). This chord is built by adding a third to a minor ninth chord.
Comparing the A Minor Scale with the A Minor 11th chord:
A Minor scale: A – B – C – D – E – F – G
A Minor 11 chord: A – C – E – G – B – D
The last group among the extended chords is the Minor thirteenth (m13). This chord is built by adding a third to a minor eleventh chord.
Comparing the A Minor Scale with the A Minor 13th chord:
A Minor scale: A – B – C – D – E – F – G
A Minor 13 chord: A - C - E - G - B - D - F#
As you may notice, all notes in the scale are included in the chord, with F# as an exception. It may seem odd that F# is a part of the chord since is not part of the scale, but the reason is that the added note is a major thirteenth.
A somewhat peculiar group is the Minor Major chords (mM or minmaj), merging Minor and Major. The most common variant connect Minor Seventh and Major Seventh, but also a merge of Minor Seventh and Major Ninth exist.
Comparing the C Minor 7th and the C Major 7th with the C Minor Major 7th chord:
C Minor 7 chord: C – Eb – G – Bb
C Major 7 chord: C – E – G – B
C Minor Major chord: C – Eb – G – B
All chords that have been mentioned can be seen in diagrams on this site.
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