Chord Scales - Part 1: The Major Scale
(07 Apr 03)
Intervals within a Major Scale
Although I dedicated an entire article to intervals ("Intervals - The Key to Harmonic Understanding") I'd like to include a quick look at the intervals of a major scale. Examining a scale by its intervalic structure is incredibly important for our goal of understanding chord scales.
Well, again in C:
Instead of thinking of a major scale in terms of whole and half steps, we now have the possibility of describing it with intervals.
Any major scale is made up of these intervals:
1 M2 M3 P4 P5 M6 M7
(Please refer to the Interval article mentioned above if you are not sure whether you understand this topic.)
Harmonized Major Scale
Now that we have dealt with major scales in horizontal direction, lets start to take a look at their vertical structure, meaning their scale internal chords.
Plain C major scale:
We start out by harmonizing the major scale with thirds that are diatonic to the scale (diatonic means part of the scale). Below I included the resulting interval starting from each scale note:
If we add another third on top we get all triads within C major:
By adding another third on top we get all 7th chords within C major:
I cannot emphasize how important the above really is. Here lies the answer to questions like "How can I transpose this tune?" or "How can I improvise over this chord progression?".
Chords Derived From Major Scales
We already learned all major scales, their structure and accidentals. In the same way we created a formula for the horizontal direction of scales, we can also create one for the vertical direction, meaning chords.
I will focus on the 7th chords because triads and intervals are part of it and easy to derive. Instead of Arabic numbers, chords are presented by Roman numerals.
Here are the 7th chords from C major with their appropriate numeric values:
Again, forget about the fact that we used C major for demonstration and take a look at the formula for the individual chords:
Imaj7 IIm7 IIIm7 IVmaj7 V7 VIm7 VIIm7b5
This formula is identical whatever scale and key you are in. If you write out all 7th chords within D major you end up with the same result regarding Roman numerals and chord quality. Here's the proof:
This means that if you know the single notes of a major scale you also know which chords the scale contains.
Major Formulas Overview
Another very helpful way of looking at the chords is to memorize them by chord quality:
I and IV are maj7 chords
II, III, and VI are m7 chords
V is a 7 chord
VII is a m7b5 chord
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