A simple, quick overview of guitar chord theory. In particular, chord construction.
This video looks at the basic chords of the major scale. Click the video to play… click on it to pause.
Chords are made by stacking 3rds on top of one another. Basically, that just means using every other note.
E.g. C to E is a 3rd – C(1) D(2) E(3). E to G is a 3rd – E(1) F(2) G(3).
Another way to look at this is to say a basic chord has a 1st (root), a 3rd and a 5th. C(1st) E(3rd) G(5th).
If you want a 6th chord, just add the 6th to the mix. C(1st) E(3rd) G(5th) A(6th).
If you want a 7th chord just add the 7th to the mix. C(1st) E(3rd) G(5th) B(7th). Note: Because the 7th in this chord is a half-step from 8, or ‘C’, this is known as a major7th interval. So the chord would be named Cmaj7.
7th chords are called 7th chords because they have the 7th added to the basic 3-note chord (triad) with a 1st, 3rd and 5th. Just add a 7th.
About 7th chords…
There are basically 3 different types of 7th chords: major7th, minor7th, dominant 7th.
This is determined by where the notes fall in the scale and the ‘quality’ of the intervals.
Minor chords are called minor because they have a minor3rd interval.
Major chords are called major because they have a major3rd interval.
Maj7 Chord: The major 7th chord has a major3rd and a major 7th.
Mi7 Chord: The minor 7th chord has a minor3rd and minor7th.
Dom7 Chord: The dominant 7 chord has a major 3rd and a minor7th.
In the key of C Major, the I and IV chords are maj7 chords – Cmaj7(I) and Fmaj7(IV).
The ii, iii, vi, are mi7 chords – Dmi7(ii), Emi7(iii) Ami7(vi).
The viii is a mi7b5 (minor 7 with a flattened 5th) Bmi7b5(vii).
The V chord is the dominant7 chord -G7(V)
So, chords symbols are Cmaj7, Cmi7, C7 to show which type of 7th chord they are.
Roman Numerals for chord position in the scale…
We use roman numerals to label chord positions in the scale.
7 chords = I, ii, iii, IV, V, vi, vii.
Upper case means major – lower case means minor.
Major: I, IV, V*. Minor: ii, iii, vi, viii*.
The V(5) chord is a major chord because it has a major3rd. What makes it unique, is the fact it has a minor 7th. It’s the only chord in the scale with a major3rd and minor7th intervals. The other major chords both have major7th intervals.
The vii(7) chord is a type of minor chord. But it has a diminished 5th. Or, a flattened 5th.
Base chord interval standard – comparing chords
When looking at the intervals in chords, we compare them to the I chord of the major scale. That’s the standard.
E.g. Let’s look at the Cmaj7 chord…
Cmaj7 = C E G B
To turn it into a dominant chord we would lower the 7th. The 7th would become Bb.
C7 = C E B Bb
The key of one flat is the key of F Major – F G A Bb C D E F C7 belongs as the V chord of F major. Counting up from F to C is 5
Cmi7 = C Eb G Bb
Now, a min 7th chord can be a ii, ii, or vi chord. So what keys could Cmi7 belong to? Answer: Bb major as the ii chord, Ab major as the iii, and Eb major as the vi chord.
Eb major is the relative major of Cmi.
Cmi7b5 = C Eb Gb Bb This chord has a mi3rd, dim5th, and mi7 intervals. So the 3rd, 5th and 7th have been flattened compared to the Cmaj7 chord.
When musicians talk about chord intervals, they usually use the terms ‘flat’ or ‘sharp’. “The minor chord has a flat(ted) 3.” Just so you know there’s a couple of ways to talk about intervals. The ‘proper’ way and the shortcut way. Proper = minor 3rd. Shortcut = flat 3.
Read Guitar Chord Secrets to get a grip on all this. But we’ll look at simplifying it all with the upcoming ‘chord-scale’ fretboard patterns. This is more important and beneficial for the practical side of it all.
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— Guitar Chord Theory: Chord Construction —
