12. CHORDS AND SCALES

Up to now, we have studied the chords as if they were independent to each other, that is, without saying which chords are related with which other chords. Generally, a melody consists of notes belonging, either to a Major or to a minor scale. On the other hand, each melody usually has an accompaniment that is normally composed by notes belonging to the same scale as the melody. And, also in a general sense, this accompaniment consists in chords built by superimposing 3^rd intervals (Major or minor) on every scale degree.

Thus, for example, a musical passage written in C Major will have an accompaniment that, in most cases, will be formed by the chords shown in Table 4. In that Table, both 3 and 4 note chords have been considered.

Table 4. C Major scale and 3 and 4 note chords associated to this scale.

The musical system of script provides us with an easy and compact way for representing both the melodies and the chords. As an example, the information in Table 4 is again shown in Fig. 18 using the music notation.

Figure 18. C Major scale and the 3 and 4 note chords associated to this scale.

Logically, Music, as in every art, has no exact rules or strict limits. On the contrary, everything is allowed and nothing is prohibited with the aim of creating beauty or, simply, producing different emotions. This means that, in a composition which melody is in C Major, we can find other chords than those above mentioned; or, we can find, even in the melody, some notes outside this scale.

Chords in Table 4 and in Fig. 18 are, simply, those associated, in a natural way, to the C Major scale. That is to say that they represent the “first option” to add an accompaniment to a melody written with the notes of that scale. Therefore, those chords are the chords that will be found, in most cases, in the scores or musical passages which melodies are created with the notes of the C Major scale. Moreover, Table 4 and Fig. 18 also tell us that the chords contained in them are affine among them. So, this way we begin to relate chords among them, instead of considering them as isolated and independent things.

If we had considered the A natural minor scale instead of the C Major scale, we would have obtained the same previous chords, but in another order, that is, assigned to different scale degrees. But if we consider the A harmonic or melodic minor scales, some different chord types will then appear. The 3 and 4 note chord types appearing in Major and minor scales are precisely all those studied in chapters 9 to 11.

The task of adding chords to a melody is known as harmonization of melodies and represents an important part in the study of Harmony. Major and minor scales, besides serving us to create melodies as well as providing the most suitable chords to accompany them, are the key to relate chords among them, for the chords associated to any Major or minor scale always form a set of chords which are affine among them.

When talking about scales and their associated chords, it is worthwhile to clarify the difference between Tonic and Root. The Tonic is “the first note of a scale” (that is, the I degree) and the Root is “the first note of a chord” (that is, the note above which the 3^rd intervals are superimposed). Therefore, in a Major or minor scale there is only one tonic, but there are 7 roots, one for each chord associated to the scale. These 7 roots are precisely the notes of the scale. The chord whose root is the tonic of the scale is called Tonic Chord. So, if considering 3 note chords, the tonic chord in the C Major scale is C; and the tonic chord in any A minor scale is Am.

On the Harmonic Wheel, the consonant chords are always grouped by couples formed by a Major chord and its relative minor chord. And each of these couples is assigned the key signature that would correspond to these chords if they were tonic chords. So, each Major or minor chord also represents a key. This fact allows us to directly obtain the key signature associated to any Major or minor scale, as was done in Chapter 7.

Knowing the chords associated to any Major or minor scale, for any number of accidentals in the key signature, is therefore a corner stone to harmonize melodies. And, because it may result very complex, in the Harmonic Wheel a very simple system to obtain all the chords associated to any scale has been implemented, as will be seen in the next Chapter. Moreover, moving a series of notes or chords from one key to another is also a complex operation that can be easily performed by using this instrument. This operation is named Transposition and is quite common in Music. However, the transposition of notes should be mentally performed, which requires the study of their associated rules and much practice as well.