How Chords are Constructed and Related

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Are you at that place where you have learned a bunch of chord pictures but you have no idea how they fit together and if they do and why?  If so this read might help you to understand some of the mechanics of music.  I have a mantra that I keep repeating to all my students and it is: “Chords come from scales”.

This simple idea is intrinsic to how our system of music functions.  If you learn to grasp this simple concept you will find that it will reveal the fabric that holds music together.

For this study we will use a G major scale as our example scale but before we do let’s define what a Major scale is.  A Major Scale is a ladder of notes with fixed distances between each note.  Those distances are made up of Tones and Semitones.  On the guitar a Tone is the distance of two frets and a semitone is the distance of one fret.  Using these distances a major scale is:

Tone     Tone     Semitone     Tone     Tone     Tone   Semitone

Try out this logic on a single string for instance, if you begin this series of distances from any given note you will end up with a major scale and that major scale will be named from the note you started on.  Let’s start the scale on a G or 3rd string beginning with open G.

Tone  A  Tone  B  Semitone  C  Tone  D  Tone  E  Tone  F#  Semitone   G

You should on the final G be an octave higher at fret XII.  You will note that the G major scale has an F# in order to maintain the correct distances between each of the notes of the major scale.

Ok, so now that we know what a major scale is let’s derive the chords from that scale.  The way we derive chords from a scale is to Take Skip Take Skip Take for a triad of notes that are thirds apart.  If we take our G major scale as our example and use this method from the 1st degree of the scale it will look like this.

G      A      B      C      D      E      F#      G

                                  Take  Skip Take  Skip  Take

                                    1                 3                 5


This process produces the G major chord, or in other words the I chord in the key of G.  If we follow this same method from the second degree of the scale:


G      A      B      C      D      E      F#      G

                                            Take  Skip  Take  Skip  Take


This spells an A minor chord, you may ask why the I chord is Major and the II chord is minor?  Let’s quickly examine that.  The distance from the G to the B in the major chord is 2 full Tones whereas the distance from the A to the C in the A minor chord is a Tone plus a semitone.


2 Tones  =   Major 3rd                                   Tone plus a Semitone  =  Minor 3rd


The distance relationships within the chords are different, Major chords have a Major 3rd from the root to the 3rd, minor chords have a minor 3rd from the root to the 3rd.  In other words the distance from the root to the 3rd of the minor chord is a semitone smaller than the distance of Root to 3rd in a Major chord.


Let’s now extrapolate the logic of building chords to every degree of the G major scale.


I –         GBD –   G Major   

II –        ACE –   A minor 

III –       BDF –   B minor  

IV –      CEG –   C Major  

V –       DF#A –             D Major  (D7)

VI –       EGB –   E minor  

VII –      F#AC – F# diminished


Now we have the seven chords that are built from the scale of G major.  Each of these chords have functions within the key which for our purpose in this study we will just call varying degrees of tension.  The tonic chord is the I chord and all chords to some degree want to gravitate back to the tonic chord.

Giving each chord in a key a number is sometimes referred to as the Nashville Number System.


The harmonic pillars of a major key are the I, IV and V chords


I –         GBD –   G Major   

IV –      CEG –   C Major  

V –       DF#A –             D Major  (D7)


The relative minor key of E minor (uses the same notes as G major) also has its I,IV and V in this case:


VI –       EGB –   E minor     or the I chord in E minor

II –        ACE –   A minor     the IV chord in E minor

III –       BDF –   B minor     the V chord in E minor


You will notice that we have left out the diminished chord and to capture that simply we make the D chord a D7 chord which is very common, by making this chord a 4 note chord the top 3 notes of the chord are a diminished triad.  ex:


D7  –  D   F#   A   C  = dim


The D7 chord is often used as the V chord.


Since all the distances of a major scale are the same in every major scale this means that the chord types derived from the scale will remain the same in EVERY Major key, in other words the chord types will always be:


Major     minor     minor     Major     Major or 7     minor     diminished


You need only add the letter names of the specific major scale to identify the chords in the key chosen, let’s take one more example of D major scale, the notes in D major are:


D tone E tone F# semitone G tone A tone B tone C# semitone D


Since the distances remain the same so will the chord types:


D Major   Emin   F#min   G Maj   A(7)   Em   C#o   DMaj


The same holds true for every major scale.  It doesn’t matter if you are playing songs by ear, lifting tunes from recordings or writing your own material this provides you with a tremendously useful and practical understanding of how chords function within a key.


Every key has its own feeling and sound so start by grouping chords in I, IV, V major and I, IV, V minor in the most common keys.


The most common keys on the Guitar


 I      IV      V   –   Major                                        I      IV     V  –   Relative Minor

 C      F     G(7)                                                      Am  Dm  Em

A      D     E(7)                                                      F#m Bm C#m

G      C      D(7)                                                     Em   Am   Bm

E       A     B(7)                                                      C#m  F#m G#m

D      G     A(7)                                                      Bm   Em    F#m


Hope you found this useful.

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