Understanding Chords

Triads & Chords


Look at C to E.  That’s  a Major 3rd.  4 half steps.  C to C# is a half step. C# to D the second half step. D to D# the third half step and D# to E making 4 half steps from C-E.

Now look at E to G, a Minor 3rd.  3 half steps.  E-F=1/2 step.  F-F# the second half step and F#-G the third half step.   Be sure you understand this. 

With these two building blocks, we can built all chords.


First we need to understand the types of chords that are possible.  The bottom 3 notes form theTriad(3 note chord) and there are 4 possible triad each composed of two 3rds..  Major chords, Minor chords, Diminished chords and Augmented chords.

Figure each chord on the keyboard to see the patters of organization of 3rds.

How do you know if you are on the 3rd of a chord or another chord member?

To figure this out, first, we obviously need to have some understanding of chords and how they are visualized on the staff.  That is the purpose of this topic.


Chords are based on a “tertian system” meaning that all chords are built on 3rds either Major 3rds or Minor 3rds.  A Major 3rd is 4 half steps and a Minor 3rd is 3 half steps.  To clearly understand this we need to visualize it using our greatest visual aid for pitch understanding - the keyboard.  Think of everything as it looks on the keyboard and it will help.

Major Chord: Major 3rd (4 half steps) on bottom, plus  Minor 3rd (3 half steps)

Minor Chord: Minor 3rd plus Major 3rd.

Diminished Chord: Minor 3rd plus Minor 3rd

Augmented Chord: Major 3rd plus Major 3rd

Then to a triad we can add further 3rds to make 7th chords and 9th chords.

The 7th chord can have any of the 4 triads as their foundation but here we have the Barbershop 7th chord: Major Triad plus Minor 3rd.

The Common 9th chord: is made up of a Barbershop 7th plus a Major 3rd

The Half-Diminished 7th Chord = a Diminished Triad plus a Major 3rd.

The half-Dim.7th chord can be best understood as an incomplete 9th chord with the root missing.

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