In music theory, the distinction is based on whether an interval occurs naturally within the Major and Minor Scales or if it requires “artificial” chromatic. (SOS: See the note at the end of the post!)
1. Interval of a 2nd
- Diatonic: Minor (E-F), Major (C-D) , and Augmented (F-G#) (found in Harmonic Minor).
- Chromatic: Diminished (C# – D♭) (sounds like a unison).
2. Interval of a 3rd
- Diatonic: Minor (A-C, F-Ab) and Major (C-E).
- Chromatic: Augmented (C – E#) and Diminished (Do# – Eb) (do not exist in any diatonic scale).
3. Intervals of a 4th & 5th (The “Universal” Diatonics)
- Diatonic:ALL (Perfect, Augmented, Diminished).
Augmented 4th (F-B): Diatonic (C Major, 4th–7th degree).
Diminished 5th (B-F): Diatonic (C Major, 7th–4th degree).
Diminished 4th (B-Eb): Diatonic (C Harmonic Minor, 7th–3rd degree).
Augmented 5th (Eb-B): Diatonic (C Harmonic Minor, 3rd–7th degree). - Chromatic: None.
4. Intervals of a 6th
- Diatonic: Major (C-A) and Minor (C- Ab, in C minor)
- Chromatic: Augmented (Ab – F#) and Diminished (C#-Ab)
5. Intervals of a 7th
- Diatonic: Minor (G-F), Major (C-B), and Diminished (B-Ab) (found in C Harmonic Minor).
- Chromatic: Augmented (C-B#).
6. Intervals of an 8th (Octave)
- Diatonic: Perfect (C-C)
- Chromatic: Augmented (C-C#) and Diminished (D-Db) .
Examples for your Study:
- F – G# (Augmented 2nd): Diatonic (found in A Harmonic Minor).
- B – Ab (Diminished 7th): Diatonic (found in C Harmonic Minor).
- C – E# (Augmented 3rd): Chromatic (not in any scale).
- F – B (Augmented 4th): Diatonic (found in C Major).
Practice:
On your Major and Minor scale worksheets, look at the final exercise regarding intervals within the scales. Up until now, we have only mentioned the names (e.g., 2nd, 3rd).
Your Task:
Whether it is Diatonic or Chromatic (based on the rules above).
Pick any one Major and one Minor scale worksheet.
In the last exercise, identify the intervals.
For each one, write:
The Size/Quality (e.g., Major 3rd, Perfect 5th)
Note: Reminder on “Diatonicism”:
We have learned the strict definition of a diatonic scale: a scale consisting of 7 notes (5 tones and 2 semitones) where the semitones are as far apart as possible. In this strict sense, only the Major (Ionian mode) and the Natural Minor (Aeolian mode) are truly diatonic scales.
However, in Classical Harmony, we use all three forms of the minor scale (Natural, Harmonic, and Melodic). Because Classical Harmony relies heavily on the Harmonic Minor (an alternation of the Aeolian), the definition of Diatonic Intervals expands:
- Diatonic Intervals: These are the intervals found in the Major scale and all types of Minor scales (Natural, Harmonic, and Melodic). Even though Harmonic and Melodic scales contain notes outside the key signature (accidentals), their intervals are considered “diatonic” within the context of classical music.
- Chromatic Intervals: These are intervals that do not exist in any of these scale forms. They are created by accidental alterations or “random” sharps/flats that do not belong to the structure of these standard scales (e.g., an Augmented 3rd).