Half Steps and Whole Steps

Notes forming a half step may be written in two ways

both notes may be written using the same letter name or the notes may be written with two consecutive letter names

In music of the West, the octave is divided into

12 equal parts called half steps, or semitones.

In non-Western music, the octave may be divided into

24 units (quartertones).

In some more modern Western music, it may be divided into

even smaller units (microtones), as in the 43-unit music by American composer Harry Partch.

The white keys on a piano are separated by

black keys except for E to F and B to C.

All adjacent numbered keys are

called half steps (HS).

Half steps are paired

white to black keys, or black to white keys, except for the two adjacent pairs of white keys (E to F and B to C).

If the letter names are different consecutive letters,

the half step is called a diatonic half step (di = two).

If the letter names are the same,

this is called a chromatic half step (chroma = color)

 A scale is

a pattern of notes.

When a scale consists only of notes that are half steps apart,

this is called a chromatic scale.

For example, the half step F to F# may also be written

F to Gb.

Properties of a chromatic scale: All pitches are

a half step apart.

Properties of a chromatic scale: When notating an ascending chromatic scale, sharps are usually used to

identify black keys.

Properties of a chromatic scale: When notating a descending chromatic scale,

flats are usually used to identify black keys

Properties of a chromatic scale: There are 12 different

pitches in a chromatic scale

Properties of a chromatic scale: The thirteenth pitch in a chromatic scale

is the octave note.

Although this is called a chromatic scale, both

chromatic half steps (C–C#) and diatonic half steps (C#–D)are used.

Note that diatonic spellings usually are used for

the two pairs of white key half steps, E–F and B–C.

Two adjacent half steps comprise

a whole step.

For a whole step, on the keyboard,

skip one key between two notes

Diatonic whole steps consist of

two half steps with adjacent letter names.