Now that we know more about intervals and scales, it’s time to put everything together and examine the relationship between scales and chords. You can learn the basics of chord construction and naming here, I’ll assume that you’re familiar with those, if not, go and read it now.

We will start with the C major scale and we’ll assign a progressive number to each note, these are the Degrees of the scale and also the intervals from the Root. The eighth degree is the same note as the root and so it’s considered another first degree and the cycle repeats. Intervals, on the other hand, continue and we will call the next C an ‘Octave’.

We saw in the Mini-course how we can build chords by stacking thirds on every note of the scale and we examined their intervals to determine their ‘quality', like Major or minor.

We’ll begin by examining triads (three-note chords) and see what we get.

The chord on the first degree is C - E - G and if we analyze the intervals, we find a Major third (2 Tones) followed by a minor third (1 tone and a half) or a major third and a perfect fifth (3 Tones and a half) from the chord’s root: this is the formula for a Major chord.

C Major

The intervals in the chord built on the second degree are inverted, minor and major third and we know this is a minor chord.

D minor

Chords built on the third and sixth degree are minor as well while the one on the fourth and fifth are major: you can calculate the intervals yourself as an exercise.

This leaves us with the chord on the seventh degree which is B - D - F. Both intervals are minor thirds so their sum gives us three tones or a diminished fifth, and we said that we call this chord a diminished triad.

B Diminished triad

Now we have the complete series of triads built on the major scale and we can start to learn what type corresponds to each degree regardless of the name of the chord or scale: we keep using the C major scale as a model since there are no sharps or flats to clutter up our score.

We start to see a simple pattern of Major and minor chords with the diminished on the seventh degree and we realize that we can use the major scale to compose a melody or improvisation over a progression of chords from this list since the notes are the same. Conversely, we can use chords from the list to play under a melody that uses the notes from the corresponding major scale. Obviously, not any chord will sound great with any note but we sure can find good matches and give our composition a sense of wholeness, of belonging together: this is basically the meaning of Tonality or what it means to play in a Key.

In the next chapter, we’ll expand the concept and analyze 7th chords.