Harmonising the Major Scale

The notes in the key of C major are C D E F G A B
The C major scale contains no sharps (#) or flats (b)
From the above 7 notes, 7 chords can be generated:

– 3 major chords C, F and G
– 3 minor chords Dm, Em and Am
– and 1 diminished chord B dim

Here is how to find the chords in any key:

Take the notes of any major scale In this case (for simplicity because it contains no sharps or flats) we are using C major

C D E F G A B

Give each note a number from 1-7

C	D	E	F	G	A	B
1^st	2^nd	3^rd	4^th	5^th	6^th	7^th

Take the 1^st(which we will call the root and will become the name of the chord), the 3^rd and the 5^th and play them all at the same time

C	D	E	F	G	A	B
1^st		3^rd		5^th

The result will be a C major chord.

Note: This is a MAJOR chord because the interval (distance) between the root (C) and the 3^rd (E) is two tones = 4 frets. This is the definition of a major chord.

Next, do exactly the same thing but this time starting from the next note of the C major scale.

C	D	E	F	G	A	B	C
(7^th)	1^st	2^nd	3^rd	4^th	5^th	6^th	7^th

Notice that now we are calling D the 1^st (the root), which makes F the 3^rd and A the 5^th

The result will be a D minor chord.

Note: This is a MINOR chord because the interval (distance) between the root (D) and the 3^rd (F) is one and a half tones = 3 frets. This is the definition of a minor chord.

If we repeat the same thing over for every note of the scale we end up with this:

Notes	Chords	Chord Number
CEG	C major	I
DFA	D minor	II
EGB	E minor	III
FAC	F major	IV
GBD	G major	V
ACE	A minor	VI
BDF	B diminished	VII

NOTE: Where the first 6 chords have a perfect 5th, the last one, a diminished chord, has a minor 3^rd and a flattened (or diminished) 5th

Each of these seven chords contains 3 notes, they are therefore known as TRIADS

To recap, all the triads below are in the key of C major and derive from (and ONLY from) these 7 notes…

C D E F G A B

This pattern is the same no matter what key you are in.

MAJ- MIN- MIN- MAJ- MAJ- MIN- DIM

The harmonised triads in the key of C major are…

To determine the key centre in major chord sequences, try looking for clues of this pattern. For example, two Major chords a tone apart are likely to be chords IV and V. From this you can then work out what chord I is, which will be your key.