Half Steps and Whole Steps
You learned before that the difference, or distance, between any two pitches is called the interval between them. There are many different intervals between the notes of the chromatic scale, depending on which two notes you choose, including the octave that encompasses them all.
For our purposes, only two other interval types need be considered:
- The smallest interval is the half step, or semitone, which is the distance between any two successive notes of the chromatic scale. On a keyboard, a half step is the interval between the closest adjacent notes, white or black. The distance from E to F is a half step; so is the distance from C to C sharp (C♯), D to E flat (E♭), and so on.
As the smallest interval in regular use, the half step is also the smallest that most people can “hear” easily and identify. Many tunes, such as “The Battle Hymn of the Republic,” end with two half steps, one half step going down and then the same one going up again (“His truth is march-
ing on”). - The whole step, or whole tone, is equivalent to two half steps: C to D, D to E, E to F♯, and so on. “Three Blind Mice” starts with two whole steps, going down.
The chromatic scale consists exclusively of half steps. The diatonic scale, instead, includes both half steps and whole steps. As you can see in the keyboard picture below, between B and C and between E and F of the diatonic scale, the interval is a half step — there is no black key separating the white keys. Between the other pairs of adjacent notes, however, the interval is twice as big — a whole step.
In this way the diatonic and chromatic scales differ in the intervals between their adjacent pitches. In the diagram below, the two scales are shown in music notation in order to highlight the differences in the intervals they contain. The mixing of half steps and whole steps is a defining feature of the diatonic scale.
