Chromatic scale: spelling, functions and use

Definition

The chromatic scale contains all 12 semitones of the octave. In equal temperament it is perfectly symmetrical and has no tonal center of its own: the key is given by the context. The term “chromatic” (from the Greek chroma, color) indicates in tonal music all the notes and chords foreign to the diatonic scale.

Spelling

Different conventions exist; all respect the principle that altered notes show their tendency.

Melodic (practical) spelling: ascending, use sharps (C C# D D# E F F# G G# A A# B C), descending, flats (C B Bb A Ab G Gb F E Eb D Db C). In keys with flats the usage is adapted.
Tonal spelling in C major (many textbooks): ascending C C# D D# E F F# G G# A A# B; descending C B Bb A Ab G F# F E Eb D Db C. The descending F# is kept because it is the leading tone of the dominant; Bb, Ab and Eb are the degrees “borrowed” from the minor.
Harmonic chromatic scale (ABRSM and British programs): each degree appears twice except tonic and dominant, and it is the same ascending and descending: on C C Db D Eb E F F# G Ab A Bb B C. It contains the notes of the major, of harmonic minor and the most common chromatic degrees (the Neapolitan b2, the #4 of the secondary dominant).

Functions of chromaticism

Chromatic passing notes: they fill in a whole tone (C – C# – D).
Chromatic neighbor notes and appoggiaturas: E – D# – E; the artificial leading tone of every degree.
Enclosures (jazz): they approach a target note from above and below by semitone (F – D# – E).
Inner chromatic lines: the “line cliché” (Am – Am(maj7) – Am7 – Am6), the rising fifth (C – C+ – C6 – C7).
Descending chromatic basses: the Baroque lament bass (Purcell, “When I Am Laid in Earth”, Dido and Aeneas), the bass of “Stairway to Heaven” and of many rock ballads.
Chromatic chords: secondary dominants, borrowed chords, Neapolitan, augmented sixths, chromatic mediants.
Twelve-tone technique: in Schoenberg’s serialism (from the 1920s) the row uses all 12 notes with equal importance, without a tonal center.

Color

Chromaticism can be expressive (lament, tension, sensuality: the Prelude to Wagner’s Tristan), virtuosic (fast chromatic scales: Rimsky-Korsakov’s “Flight of the Bumblebee”), comic or unsettling (ascending chromaticism in cartoon and horror film music).

Use in production

Risers and build-ups: an ascending chromatic scale (or a continuous pitch sweep) raises tension before the drop.
Bass: a chromatic approach passage (E – F – F# – G) before a chord change makes the bass sound more “played”.
Glide: the portamento of a mono synth crosses the chromaticism continuously.
Vocal melodies: chromatic passing notes on weak beats (even just one per phrase) add refinement to a diatonic topline.

Examples in real pieces

Rimsky-Korsakov, “Flight of the Bumblebee”: continuous chromatic scales.
Wagner, Prelude to Tristan und Isolde: the ascending chromatic line G# – A – A# – B in the opening.
Purcell, “When I Am Laid in Earth”: descending chromatic bass (lament) over an ostinato.
Led Zeppelin, “Stairway to Heaven” (intro): A – G# – G – F# – F in the bass under Am.
“Something” (The Beatles): the chromatic inner voice C – B – Bb – A over C – Cmaj7 – C7 – F.

Common mistakes

Writing chromatic notes with the wrong spelling: it makes reading difficult and hides the function.
Using chromaticism on strong beats without intention: it sounds like mistakes.
Overdoing it: a completely chromatic melody loses tonality (sometimes intended, but it must be controlled).

Exercise

Write the harmonic chromatic scale on D and on Bb and compare it with the melodic spelling.
Add to one of your diatonic basses three chromatic approach notes on weak beats before the chord changes.
Create an 8-bar build-up with an ascending chromatic line in the synths and a noise riser, then the drop on the tonic.

Accidentals; Enharmonics; Non-chord tones; Bebop scales; Set theory (1); Reharmonization.