Note: This material on diatonic modes was developed back in 1992, as part of a music theory compendium I used to hand out to my guitar students. As a guitar teacher, one of the most requested topics I got asked over and over, was to help my student understand modes, and how to use modal theory in their playing.

Diatonic Scale Patterns

In western music, the spacing of notes are based on an even twelve step division per octave. Each of these twelve steps is called a semitone. These semitones are often reflected in our western instruments. The frets of a guitar is spaced into semitones, and so are the keys on a piano. If we play all semitones in an octave, we are playing a chromatic scale. By jumping over a semitone, we can play a whole tone interval. If we play a scale consisting of only whole step intervals, we are playing a whole tone scale.

Then we have scales consisting of both semitone and whole tone intervals. These are called diatonic scales.

Modes

Modal scales are derived from a specific combination of seven diatonic intervals consisting of five whole tones and two semitones. The specific order of these tones are three whole tones, a semitone, two whole tones, and a semitone. Depending on which note we set as the tonic (starting note), we will get seven different inversions (modes) of this scale pattern.

  1. Lydian: Three whole tones, a semitone, two whole tones, and a semitone
  2. Ionian (Major): Two whole tones, a semitone, three whole tones, and a semitone
  3. Mixolydian: Two whole tones, a semitone, two whole tones, a semitone, and a whole tone
  4. Dorian: One whole tone, a semitone, three whole tones, a semitone, and a whole tone
  5. Aeolian (Minor): One whole tone, a semitone, two whole tones, a semitone, and two whole tones
  6. Phrygian: One semitone, three whole tones, a semitone, and two whole tones
  7. Locrian: One semitone, two whole tones, a semitone, and theee whole tones

So, starting a scale from each note of the diatonic scale, gives us a different mode (see fig. 1).

Fig. 1 - Understanding Music Modes: Location of modes in relation to the diatonic scale

If we take the diatonic scale in the key of C, we get C-Ionian (which is the same as the C-major scale), D-Dorian, E-Phrygian, F-lydian, G-Mixolydian, A-Aeolian (which is the same as the A-minor scale), and finally B-Locrian (see fig. 2). All these modes share the same key, notes and chords - however, they sound completely different in their modal context.

Fig. 2 - Understanding Music Modes: Location of modes in relation to the C-major scale

Modal Context

In western music, we usually think in terms of major or minor keys. And most people who either play an instrument or sing, understand the theory behind C-major and A-minor sharing the same notes and chords; as in A-minor is the parallel key to C-major. It is also clear to most, that C-major and A-minor doesn't sound the same. They provide their own distinct musical context.

Music written in a major key usually appears to be uplifting and happy, whereas music written in a minor key sounds more mellow and sad. If we now think of these as two of the modes (ionian and aeolian), we understand that the other five modes also bring their own distinct musical context.

Lydian has a very light feel to it. Sometimes described as blissful or meditative sounding. Dorian might be considered melancholic, mysterious, thoughtful or reflective. Mixolydian has a more heroic feel to it, and is often used in music surrounding sports events. How we perceive these contexts is somewhat individual of course, and can vary based on the musical composition and arrangement elements too. The point is, that the seven music modes gives us more tonal contexts to work with than only major and minor. In fact, we have three major modes and four minor modes (see fig. 3).

Fig. 3 - Understanding Music Modes: Accidentals in relation to the C-major scale

As we can see from the figure - Lydian, Ionian and Mixolydian have the major third interval in relation to the tonic. Whereas Dorian, Aeolian, Phrygian and Locrian all have the minor third interval in relation to the tonic.

Here are the different modes we get from the C-tonic, in relation to the corresponding key (see fig. 4).

Fig. 4 - Understanding Music Modes: Accidentals on all C-modes

"Lighter" And "Darker" Modes

It's easier to see what's going on if we sort the modal scales from "light" to "dark". For each mode we go down, one note is changed (see fig. 5).

Fig. 5 - Understanding Music Modes: C-modes sorted from light to dark