Triads

Triad Chords found in the Major Scale

The Major Scale contains seven triads (3 note chords). In order to see what they are, let's look at the C Major Scale...

The first chord in C, is obviously C Major, it's made up of the notes C, E and G. Following this pattern the next chord that we find in the scale of C Major is D, F and A which is the chord of D Minor. Then we have E, G and B which gives us E Minor. Next up is F, A and C which is F Major. Then G, B, D or G Major. Then A, C, E, A Minor (which is the also relative minor of C Major). The last chord is B, D and F which contains both a flat 3rd and a flat 5th, which gives us a Diminished Chord, in this case B Diminished.

Here's how each chord looks on the Fretboard...

C Major (C, E, G)
G Major (G, B, D)
D Minor (D, F, A)
A Minor (A, C, E)
E Minor (E, G, B)
B Diminished (B, D, F)
F Major (F, A, C)
 

But what about the other Keys/Scales?

The other scales/keys also contain 7 (maj, min, dim) triads, they always follow the order: Major, Minor, Minor, Major, Major, Minor and Diminished.

For easy reference, here's a chart of all the keys and associated triads...

KEY I II III IV V VI VII
C# C# D#m E#m F# G# A#m B#
F# F# G#m A#m B C# D#m E#
B B C#m D#m E F# G#m A#
E E F#m G#m A B C#m D#
A A Bm C#m D E F#m G#
D D Em F#m G A Bm C#
G G Am Bm C D Em F#
C C Dm Em F G Am B
F F Gm Am Bb C Dm E
Bb Bb Cm Dm Eb F Gm A
Eb Eb Fm Gm Ab Bb Cm D
Ab Ab Bbm Cm Db Eb Fm G
Db Db Ebm Fm Gb Ab Bbm C
Gb Gb Abm Bbm Cb Db Ebm F
Cb Cb Dbm Ebm Fb Gb Abm Bb

Triad/Note Realtionships

What this also shows us, is that each Note has 6 associated chords. If we loose the obscure keys (Db, Gb, Cb) and use their 'Enharmonic' partners instead C#, F# and B, we can formulate a pattern which shows every note surrounded by the 6 chords it's contained within, like so...

Take C, for example. It's obviously contained within C and C minor, but you'll also find it in F, Fm, Am and Ab.