Chords are made up of thirds in most cases

Chords are made up of thirds in most cases, usually falling on the root (1^st), 3^rd and 5^th notes of the scale. With all three tone centers being used in this configuration, known as a triad, we have our most used chord. The tonic (I), or major triad, in C major is C E G.

Breaking up Chord into Intervals of 3notes: (from left to right)

A Major Full chord

5^th plus 4^th

4^th plus 3rd

3^rd Major A

3^rd Minor A

A Major

Notice how the 5^thplus 4^th does not contain any 3^rd notes

Notice how the 4^th plus 3^rd root note is the center of the chord

Notice how the Major and Minor 3^rd triads only difference are the 3^rd notes by (+/-) one #

E Major

Tonic for E major

E G# B

Tonic for E minor

E G B

A Major

Tonic for A major

A C# E

Tonic for A minor

A C E

D Major

Tonic for D major

D F# A

Tonic for D minor

D F A