Chromatic scale

A musical scale that divides an octave into twelve pitches, each a semitone apart. It includes every pitch class used in standard Western equal-tempered music.

Semitone: The interval between adjacent pitches in the twelve-tone equal-tempered system. Each step of the scale advances by one semitone.
Musical notation: A system of symbols for representing musical sounds, durations, and performance instructions. Staff notation represents chromatic pitches with accidentals and key signatures.
Pythagorean tuning: A tuning system that builds intervals from ratios of small whole numbers, especially perfect fifths. Its uneven semitones contrast with the equal steps of modern chromatic scales.
Chromatic keyboard: A keyboard layout that provides access to all twelve pitch classes within an octave. Its arrangement makes each step of the chromatic scale directly playable.
Diatonicism: The organization of music around seven-note diatonic scales and their tonal relationships. Diatonic practice selects seven pitches where the chromatic scale includes all twelve.
Octave: The interval between two pitches where the higher has twice the lower pitch’s frequency. The twelve semitones span one octave before the pitch sequence repeats.
Accidental (music): A notation symbol that alters a note’s pitch from its key-signature form. Accidentals mark the chromatic notes that depart from a diatonic collection.
Mean-tone temperament: A family of tunings that adjusts fifths to produce purer major thirds. Mean-tone systems shaped how chromatic notes sounded and which keys were usable.
Twelve-tone technique: A compositional method that organizes music around ordered series of all twelve pitch classes. It treats the chromatic collection as a basis for systematic composition.
Just intonation: A tuning approach using intervals formed from simple whole-number frequency ratios. Its pitch relationships do not generally produce twelve equal semitones.

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