Chord theory is a fascinating topic. Understanding what chords are and how they are constructed on the guitar can really open your mind to a new world of possibilities.
The reason why major scales are so important is becuase it is from that particular scale that chords are constructed.
A major scale is simply 7 notes separated by intervals (tones and semitones):
Root Note (starting note) – Tone – Tone – Semitone – Tone – Tone – Tone – Semitone (starting note again, but up one octave).
So if we were to play a C major scale it would look like this:
C – D – E – F – G – A – B – C (up octave)
If we were to play an A major scale it would look like this:
A – B – C# – D – E – F# – G# – A (up octave)
Any major chord is simply the 1st, 3rd and 5th notes of a major scale. That’s it!
So, from the information above, a C major chord is simply the notes C, E and G (1st, 3rd and 5th) played in unison. An A major chord is simply the notes A, C# and E (1st, 3rd and 5th) played in unison.
In summary, any chord is a specific combination of notes from a major scale. The only tricky thing is that these notes can be altered (raised or lowered). I think this will make sense if we look at a list of some chords and what notes they contain. This is not an exhaustive list but contains most of the standard chords that you will come accross.
Major (1, 3, 5)
Minor (1, b3, 5)
Diminished (1, b3, b5)
Augmented (1, 3, #5)
Major 7 (1, 3, 5, 7)
Minor 7 (1, b3, 5, b7)
Dominant 7 (1, 3, 5, b7)
Diminished 7 (1, b3, b5, bb7) – yes, it has a double flat!
Half Diminished (1, b3, b5, b7)
Minor Major 7 (1, b3, 5, 7)
Augmented 7 (1, 3, #5, b7)
There are a lot more chords than this but if you can understand what is going on with the above chords then you are well on your way to understanding chord construction. You should notice that most chords have 1, 3 and 5 as a kind of ‘core’. Those notes might be altered (flat 3 or sharp 5 etc.) but they are still based around the original 1 – 3 – 5.
To make sure we understand what is going on, let’s do another example:
The notes in the key of G are (G major scale):
G – A – B – C – D – E – F#
If we wanted to play a G minor 7 chord, we would need 1, flat 3, 5 and flat 7.
1 is G
3 is B, therefor flat 3 is Bb.
5 is D
7 is F#, therefor flat 7 is F (natural)
So the four notes are:
G – Bb – D – F
We have just constructed a G minor 7 chord! Keep in mind that this is all just theoretical at this stage. We have not yet executed any of these chords on guitar, we have just figured out the notes involved. You might be thinking, ok, so C major has 3 notes, C – E – G, but the C major I know uses every string on the guitar, how does that work? The reason why this happens is because when we actually play chords on the guitar, we typically double up on notes.
Let’s look at an open C major chord.
As you can see, we have the notes C, E, G, C, E.
There are 5 strings being played, but the only notes contained are C, E and G (1, 3 and 5). It does not matter that some notes are played twice and others once. All that matters is the 1, 3 and 5 are contained in the chord.
Let’s look at another example. Bb minor 7 chord. This is a root 6 bar chord played on the 6th fret.
The notes in a Bbm7 chord are Bb – Db – F – Ab (1 – b3 – 5 – b7)
If we look at the notes in this particular shape we have Bb – F – Ab – Db – F – Bb. What this shows is that the notes do not necessarily need to be in a particular order. As long as the 1-b3-5-b7 are in the shape and nothing else, you will be playing a minor 7 chord. The order of notes and choices of double ups etc definately affect the sound and much could be written about the application of this, but for now, just think of it like this: Any two chords with the same name are the same chord, but the voicing of the chord can change the shade of color. So an open A7 chord is the same as a Bar Chord A7 chord but they are slightly different shades of the same color.
A great way to practice chord theory is to analyse chords you already know and then try to figure out and understand the notes involved. This can be a very fascinating experience and it really sharpens your ‘musical IQ’, as you are constantly thinking about the notes you are playing and the theory behind the chord that is involved.
Another great thing to do is to think of a chord and then try to construct that chord yourself. This is kind of the revearse process of analysing a chord you already know but it uses the same skills.
As I said, it is a very fascinating thing to do and can give you a real sense of creativity over the guitar. Both methods require that you have a pretty good knowledge of the fretboard.
It should also be said that this is really just an introduction to chord theory and does not even scratch the surface of why, for example, certain chords work well together in a chord progression etc. We have really only focused fpr now on how to construct chords.