Chord construction using the minor scale

Question

Background information (leads onto my question)

Here is a table of the A minor scale + the suggested chord qualities (the qualities were copied from the Wikipedia page on Roman Numeral Analysis where it discusses the minor scale; the rest of the table is something I've put together so it could have mistakes within it):

My understanding on the theory of chord construction, was thus:

Given a scale (e.g. the major scale). Split it into thirds. Note the semitones between the thirds and then apply those intervals to the scale of the relevant chord you wish to construct

This appears to work for me when constructing a chord from the major scale (i.e. all the chord qualities I ended up with, matched those noted by the relevant roman numeral analysis for a major scale)

But when I applied this same logic to a minor scale (in this case the A minor scale) I ended up with the following chord qualities (when selecting the 1, ♭3, 5, ♭7 degrees to construct chords out of):

• A: minor seventh chord √
• C: major seventh chord √
• E: minor seventh chord X
• G: dominant seventh chord X

Notice the last two chords do not match up to what was defined as the expected chord qualities for a chord constructed from the minor scale.

My question...

My question is this: using the following logic, have I constructed the chords correctly and thus the resulting chord qualities are correct or have I misunderstood the logic for minor scale chord construction. If I have, then could I get some clarification on what you think I might be missing.

Here was my logic for getting to these chords...

A chord example

The A is the 1st degree of the A minor scale and so we have to start at that degree:

1st degree -> 3rd degree == 3 semitones (minor third)
3rd degree -> 5th degree == 4 semitones (perfect 5th)
5th degree -> 7th degree == 3 semitones (minor seventh)

If we now apply these semitones to the A minor scale (A, B, C, D, E, F, G, A) we get the notes back for our chord:

A, C, E, G

These follow the degree pattern of a minor chord: 1, ♭3, 5, ♭7.

C chord example

The C is the 3rd degree of the A minor scale and so we have to start at that degree.

So again we split the scale up into thirds, but this time starting from the 3rd degree:

3rd degree -> 5th degree == 4 semitones (major third)
5th degree -> 7th degree == 3 semitones (perfect 5th)
7th degree -> 2nd degree == 4 semitones (major seventh)

If we now apply these semitones to the C minor scale (C, D, E♭, F, G, A♭, B♭, C) we get the notes back for our chord:

C, E, G, B

These follow the degree pattern of a major chord: 1, 3, 5, 7

We know a Minor Third (m3) is 3 semitones from the tonic.
Meaning the 3rd degree from this chord's root is actually a Major Third (M3).
Hence the E♭ from the scale ends up being sharpened to an E.

We also know a Minor Seventh (m7) is 10 semitones from the tonic.
Meaning the 7th degree from this chord's root is actually a Major Seventh (M7).
Hence the B♭ from the scale ends up being sharpened to a B.

E chord example

The E is the 5th degree of the A minor scale and so we have to start at that degree:

5th degree -> 7th degree == 3 semitones (minor third)
7th degree -> 2nd degree == 4 semitones (perfect fifth)
2nd degree -> 4th degree == 3 semitones (minor seventh)

If we now apply these semitones to the E minor scale (E, F♯, G, A, B, C, D, E) we get the notes back for our chord:

E, G, B, D

These follow the degree pattern of a minor chord: 1, ♭3, 5, ♭7...

G chord example

The G is the 7th degree of the A minor scale and so we have to start at that degree:

7th degree -> 2nd degree == 4 semitones (major third)
2nd degree -> 4th degree == 3 semitones (perfect fifth)
4th degree -> 6th degree == 3 semitones (minor seventh)

If we now apply these semitones to the G minor scale (G, A, B♭, C, D, E♭, F) we get the notes back for our chord:

G, B, D, F

These follow the degree pattern of a dominant chord: 1, 3, 5, ♭7...

Answer 1

Some chords in the table are incorrect: The fifth is a minor chord and the flat seventh is a major chord. Regarding seventh chords, the chords in the natural minor (Aeolian) scale are: im7 iim7b5 bIIImaj7 ivm7 vm7 bVImaj7 bVII7. To build a basic triad or seventh, you take the root of the chord that you want to build from, and stack thirds in the scale: 1-3-5-7-2-4-6-1 is the order of thirds, regardless of the alterations. In the natural minor scale, which is 1-2-b3-4-5-b6-b7, the order is 1-(m3)-b3-(M3)-5-(m3)-b7-(M3)-2-(m3)-4-(m3)-b6-(M3)-1. This tells you the chords in the scale, as you just take three in a row for a triad or four in a row for a seventh chord (or more if you're going for 9th, 11th and 13th chords).

Hope this helped!

Answer 2

You are using the natural minor scale notes. These are exactly the same as the relative major notes. Thus, for A minor, read the notes of C. There's no need to get so complex! The triad and 4 note chords made from each must be the same, as they both contain the same notes, and the chords are built on alternate notes. So, in C maj, you have Cmaj7, Dm7, Em7, Fmaj7, G7, Am7 and Bo. Putting them in a circle may make it seem simpler, but in Am all the same chords apply.

There are two more minor scale group notes, though. Melodic and harmonic. These are different: melodic starts like natural, 1-5, then uses major notes for 6&7. Harmonic starts the same as natural, 1-6, then raises the 7th. These scale notes will produce different chords, due to containing different notes - even though they are 'the same key'. Example is chord built on the 5th note - compared with the 5 chord from natural minor, using the other two it will have a major 3 rather than the minor 3.

The chord qualities in the top table are incorrect - E will be Em7, and G will be Gdom7. That's if the top letter names are correct. There's no G# in that (natural) minor, so the V (E) cannot contain a maj3.

Answer 3

You seem to be using a terribly complicated version of 'make chords using the notes of the scale'!

Yes, the natural minor scale gives us a minor chord on the 5th degree. Yes, we often (but not inevitably) change it to major, in order to get a dominant function.

It is interesting, useful even, to know what chords may be constructed from the notes of a scale. But in real music we use other ones too.

Answer 4

The chart gives triad qualities, but the text gives seventh chord qualities. This isn't a big problem, but it makes unclear what style of harmony to are interested in. All seventh chords is indicative of jazz.

Regardless, I think the main point about minor harmony can be made by simply looking at the E chord, the dominant of A minor.

The question asks about minor not Aeolian mode and that is significant. We are dealing with the major/minor system not modal harmony.

Let's some detail of the original post...

If we now apply these [intervals] to the E minor scale (E, F♯, G, A, B, C, D, E) we get the notes back for our chord:

and

If we now apply these [intervals] to the G minor scale (G, A, B♭, C, D, E♭, F) we get the notes back for our chord:

This method of building a natural minor scale over the root and then building the chord from that scale is not how the major/minor system works.

The first problem is setting each scale degree as a new tonic. For example, when you get to scale degree G in A minor you do not make G a new tonic with a G minor scale. You simple move up the A minor scale starting on G. Technically, you can call this the 7th mode of A minor. (The quality of that mode is Mixolydian.)

Second, building chords by stacking up thirds from a fixed scale of tones is a bit misguided and can lead to a misunderstanding of harmony. This is especially the case in minor key harmony.

Stacking up thirds from a fixed scale will produce only diatonic chords. The major/minor system is not a purely diatonic system. It is a combination of diatonic and chromatic harmony. The chromatic aspects are largely a matter of convention rather than a purely logical system. You can't simply use some methodical approach to know what those conventions are. You have to acquire the knowledge from score, a teacher, or good books.

Let's consider the chord on E the dominant scale degree.

If you create a purely diatonic triad on the dominant it will indeed be tones E G B which is a minor triad. This chord may be encountered in a progressions like i v6 iv6 V.

But in the major/minor system an authentic cadence must be from a major dominant chord to the tonic chord: V to i. To create that major dominant triad we use tones E G# B. You can also see the major dominant in jazz progressions like iim7b5 V7b9 imin7.

...have I misunderstood the logic for minor scale chord construction.

Yes. Again the problem is problem is trying to stack thirds from fixed scales and overlooking how to handle the dominant chord.

The best way forward is to read a good harmony textbook and study the section on minor key harmony. I think every harmony text I have seen has a separate section to deal with minor harmony, because of its unique characteristics.

If you want a reasonable rule of thumb for classical, common practice minor key harmony...

• use the diatonic chords of the natural minor scale
• in classical, common practice style when a cadence is formed the dominant chord's third should be major
• if you want to temporarily tonicize one of the non-tonic chords (III iv v V VI VII) precede it with a major triad or dominant seventh chord rooted a perfect fifth above, or a diminished chord root a half step below.

Those three points will not account for all minor key harmony, but it will cover a very large portion of it.

In jazz or pop styles, keep in mind that some minor tonalities will be minor key while others will be modal. Patterns like iimin7b5 V7 imin7 indicate a minor key flavored approach where within the pattern we see chromaticism with the dominant and the ^7 scale degree and it roughly conforms to the rule of thumb above. But, patterns like i bVII i or ivmin7 imin7 vmin7 indicate a modal approach where the chords within the pattern are diatonic. Purely diatonic minor suggests modal harmony.