Triads from each note of the major scale
Take the major scale: C – D – E – F – G – A – B – C
Build a triad starting from each note of the major scale taking two more notes from the scale, skipping a note in between. These chords are called diatonic chords – meaning ‘within the scale’
Example: forming a triad from the C note
Form a triad chord from C by choosing notes from the scale:
1. Start from C
2. skip D
3. take E
4. skip F
5. take G
We get the notes C E G which forms the C major chord.
Diatonic chords from the C major scale
The Safe chords
Since each of the chords C Dm Em etc found above has notes from the C major scale, these chords are the ‘safe chords’ which you can play for songs in the C major scale.
Of course you have to check if the chord goes along well with the particular melody notes and if that is the sound you want. But these chords narrows down the options which we have to parse through, helping much in on the fly chord improvising situations and improving our understanding of arranging and harmonizing.
Why are diatonic chords useful?
For example when singing a song in C major, and the main melody note for which you want to play chord be E:
- The E note is present in C major, E minor and A minor chords.
- You have three chord choices, none of which will be 'wrong' while you can choose which one you want.
- If you are playing C for the bar before this change to E note, try Em or Am and decide which sound you want.
Being able to restrict choices based on the diatonic chords saved you from having to consider the vast number of possible chords which had E in it.
Diatonic chords of the minor scale
The A natural minor will have the same set of diatonic chords as the C major scale since both of them have the same notes in them.
A minor scale: A B C D E F G A.
C major has: C D E F G A B C
When you choose three notes from the A minor scale skipping one note in between, you will get the same chords from both the A minor scale and C major scale.
Knowing the diatonic chords for the major scale lets you try them on the songs of it's relative minor too.
The harmonic minor scale detail
Most often, songs in the A minor scale will have the chord E major. This is the Vth chord with respect to the root A. The diatonic chord of A natural minor scale is E minor, and not E major, but the chord E major is used for harmonic importance.
The V to i motion is important for harmony. The fifth chord has to be a major (E major) and not a minor (E minor) for the 'perfect cadence' to work out, giving the beautiful tension that is an integral part of why music is enjoyable. Therefore, the G# note is introduced in the A minor scale notes to form the E major chord.
Em: E G B
E major: E G# B
Just remember that, when you are using the diatonic chords of a major scale on the relative minor scale, you may want to use the V major chord along with the others.
Example D major scale and B minor scale chords
Diatonic chords of the D major scale: D Em F#m G A Bm C#dim
Diatonic chords for the B minor scale: Bm C#dim D Em F#m G A
When playing the chords for a song in B minor scale, you may want to use F#major as the fifth chord, in the V to i motion: F#m to B minor.
(more details on harmonic minor and V to i in another post)
Chords for a large number of songs
A lot many songs are based on the major scale or the minor scale. You now know how to find the diatonic chord of a major scale from any root and use if for the relative minor scale songs too.
1. verify that D FA forms a minor chord. (check if the third note is a minor or a major 3rd)
2. verify that B D F is a diminished triad
3. write down the E major scale (first write down the sequence from E to E, write down the intervals associated with each note, see the interval formula for major scale, choose the notes based on the formula).
4. Find the diatonic triads of the E major scale by starting from each note, taking two more notes in the scale skipping one note in between.
5. Which major scale will have Em F#m and G as diatonic chords?
6. Which major scale will have Dm C B flat and Am as diatonic chords?
More about chords? Master chords using the chord code.