From the outset it is important to be clear that there are different scales that produce different rules, however the major scale is the most common in Western music by far, so that will be the focus.
Also, these are just the rules of what naturally fits into a major scale. At no point does it mean that anything outside of that is wrong. This is about music, not a mathematical equation. However, if you're breaking the rules, it's always best to know how or in what way.
Some of the concepts here can get quite advanced, so if you feel lost at all, be sure to go back and brush up on the more foundational concepts before moving on. It's not a race, getting a proper understanding is much more important than just getting through the material.
The Major Scale
The major scale consists of 7 notes:
Root, M2, M3, P4, P5, M6, M7
From the root note, the intervals move as follows:
Tone, tone, semitone, tone, tone, tone, semitone.
T T S T T T S
For our more difficult friends in 'Murica:
Tone = whole step
Semitone = half step.
Hopefully this image will help break that down a bit more:
Determining The Chords
In this blog we will go over the different chords built from each note in the scale, but before that lets look at the theory behind it.
Once you understand the different intervals (found in part 2), know the foundation of the chord (part 1-4), and you understand how the scale is laid out (see above), it is quite easy to determine where any chord fits in a scale, or more so, what chords can be built from any note within a scale.
For example, let's look at the C Major scale (as it's the easiest).
C D E F G A B C
Then, for example, I want to build a triad from the 2nd degree and determine whether it is major or minor, here is what I would do:
We can see the 2nd degree is D, the 2nd note in the scale. The 3rd of the chord built from D will be 2 away; F, and then the 5th another 2 away; A
Quite simple. So how do I determine whether it is major, minor or diminished?
Remember our musical alphabet from part 1? Well here it is again. This can help you initially (you want to grow out of relying on this) determine the size of each interval and therefore the characteristics of the chord. In this case we can recognise that D-F is 1.5 tones - a minor third, and that D-A is 3.5 tones - a perfect 5th. This minor 3rd and perfect 5th make the characteristics of a minor triad.
You can also look at the scale make up (T T S T T T S). This can show you that from the 2nd degree, in this case D, to the 4th degree, in this case F, is 1.5 tones, or a minor 3rd, and that the 2nd degree to 6th degree (D-A) is 3.5 tones, or a perfect 5th.
This second way of thinking about it is much more helpful in terms of understanding the chords in relation to the scale and so therefore being able to apply the theory to different keys.
However, either of these ways can help us determine that the triad built from the 2nd degree of the C major scale is a D minor (D, F and A).
This process is easily repeatable as long as you know the theory of building the actual chord, intervals and the musical alphabet.
What Are The Chords!
Because I'm super kind and not a meanie, this is the breakdown.
For triads (in Roman numerals):
I - major
ii - minor
iii - minor
IV - major
V - major
vi - minor
vii - diminished
Yes, you probably noticed that the roman numerals weren't capitalised for the minor or diminished chords.
For 7th chords:
I - major 7
ii - minor 7
iii - minor 7
IV - major 7
V - dominant 7 (remember part 3 where we talked about the 5th always being the dominant)
vi - minor 7
vii - half diminished 7 (also part 3 we talked about the half diminished 7 fitting naturally in the major scale).
Knowing this can also help determine what key you are playing in. For example, there is only one spot in the major scale where two major chords are next to each other, so if you are playing a song with A major and B major chords, it is most likely they are the IV and V chords, making the key E. Once you learn the characteristics of the chords within the major scale, this is much easier.
For the more complex chords, such as 9th, 13th, major 7#11 etc.it CAN be quite simple to determine will fit naturally within the scale. For example, if you want to determine whether a chord from the 6th degree will have a perfect 4th or a #11. Simply move 3 spaces from the 6th degree (along the TTSTTTS line). You will see that it is 2.5 tones, therefore a perfect 4th/perfect 11th. Repeat that process with other possibilities.
This is where it can get quite 'modal', but that may be another series for another time.
Wow, you made it, congratulations!! Please comment, subscribe and tell your friends etc. If you've just dropped in on this blog, don't forget to check out the other posts in this series:
Also, don't forget to check out the resources page, the more practical side where you can learn many of the chords looked over in this series, great for teachers and students! And also, remember to contact me for lessons, skype lessons are available!!