Principle Chords and Scale Tone Chords
Sometimes roman numerals are used in conjunction with chord symbols to help you understand the function of each chord and how they are related to each other. This is particularly useful for short progressions and turnarounds because it makes it a lot easier to memorize them and transpose them into different keys.
The three principle chords in each key are:
For example, in the key of C:
The three principle chords are C, F and G7 on the cycle of fifths. If you pick out any chord and call it the tonic ( I ) chord, the sub dominant ( IV ) chord is the next chord in a counter clockwise direction. The dominant seven chord is the next chord in a clockwise direction.
For example, in the key of A the three principle chords are:
The three principle chords in minor keys can also be found in the same way, but the I and IV chords will be minor chords.
For example, the three principle chords in the key of A minor are:
The following table illustrates the complete scale tone chords in the key of C. Scale tone chords are constructed from the notes of the major scale. Basic chords are constructed by combining notes that are a third apart.
Notice that the chords are named according to their root note (and hence use the root note’s scale). However, they are all C scale tone chords because they contain only notes of the C scale (i.e., no sharps or flats).
From this example, the scale tone chords for any key will be:
