The Major Key
The foundation of every key always consists of a major scale.
The major key accordingly consists of the major scale.
Many can probably even sing this scale. Just think of “Mary Had a Little Lamb” and continue the scale.
On the guitar, you play this scale as follows:
On the piano, accordingly, only the white keys (starting on the low C up to the high C):
C Major Scale piano And it will sound something like this
Creating Chords
Now that we know which notes are “allowed”, let’s use these notes to build our chords. We’ll notice that the same chords keep appearing.
We’ve already looked at this several times. For example, here, here, or here.
To form a chord, we need the root note, a third, and a fifth. As complicated as this may sound, it simply means we only need the first, third, and fifth notes of the scale to “generate” a chord.
Now the same applies starting from the second note. Even though the second note in the scale is counted as the second note, we consider this second note as our new root note.
D Minor Chord
This would then be a “D minor” chord.
But why a “major” chord when I start from the first note and a “minor” chord starting from the second note?
The reason is, if we start from the note “C”, the intervals are as follows:
1, 3, 5 (root, third, and fifth).
The notes that sound are: C, E, G.
The distance from C to E is a major third, the distance from C to G is a fifth.
But if I start from the second note and do the same, skipping every other note to generate a chord, I play these notes:
D, F, A.
The difference now is that the interval between D and F this time is a minor third. From D to A, the interval remains a fifth.
The reason for this is the semitones.
For example, the distance between C and D is always a whole tone. Also between D and E. However, between E and F there is always a semitone.
Accordingly, the scale and the associated chord change when I start from a different note.
Practical Example
I’m now playing the first scale, “Ionian,” over the first chord, “C Major.”
Now I start from the second note, but play the exact same notes as in C Ionian.
Since the distances between the individual notes and thus the intervals change, we get a new scale.
We also get a new chord when we play the first, third, and fifth notes of this new scale together.
Exactly the same with the next scale, starting from the third note. This results in E Phrygian and the chord E Minor.
We’re back in major when we start from the fourth note.
Starting with the fifth note, we are still in major.
Starting from the sixth note, we are in the relative minor key. The scale for this would be Aeolian. However, the minor pentatonic scale is also well-known here.
The last scale is Locrian over the diminished chord.
You can now write down the notes from C to C yourself (preferably a few octaves) and play them on the piano or guitar to find out how the distances, intervals, and chords work and why these are the exact scales that result.
You can find a list of the scales here:
Our main scale is always C Ionian. This is because we are in the key of C Major. So we always start from the C Major scale (C Ionian).
Incorrect Approach
I’ve heard of students who always reduce everything to the key. For example, if the question is about the F Lydian scale.
The best way now would be to know the distances and/or intervals of the Lydian scale.
It makes less sense to calculate the key (F Lydian is the IVth degree of C major) and start from the fourth note of that scale.
While this approach is clever and saves a lot of practice on scales, it makes practical playing extremely difficult. You’re simply too slow if you have to calculate like that every time.
Wrong Scale over Chord
What happens if I play the “wrong” scale over a chord?
Let’s say we’re in the key of C major. An F major chord is playing, and you play C Ionian over it.
The fact is, it works!
Why?
The reason is, as discussed above, they are the exact same notes. You’re just starting from a different note.
It’s definitely recommended to always start from the “right” note. So if you’re playing a C Ionian over an F major chord, you’re thinking in C Ionian.
It would be better to play F Lydian and also think in that chord.
Knowing arpeggios is very helpful here, as you always have an “escape route.”
So in order to play any scale from the key over another chord, you first need to train your ear.
A teacher once told me that a beginner always plays only C Ionian.
The semi-pro always plays the right scale over the right chord (e.g., C Ionian over C major, F Lydian over F major, etc.).
The pro, on the other hand, only plays the C Ionian scale.
But why is that?
Once your ear is good enough, you can play any scale. Theoretically, even a wrong scale that has nothing to do with the chord or the key. You just have to know your way out and land back on the root note.
Cheatsheet
You can download a cheatsheet with the notes, chords, and diagrams here.
