The Chromatic Scale is an example of a nondiatonic scale which is a scale that doesn’t observe the interval sequence of the diatonic scales.

The Chromatic Scale is a nondiatonic scale that consists entirely of half steps.  Because of these the scale has no tonic.  If you where to play every key or every fret on after another on a piano or guitar you would be playing a chromatic scale.

A – A# – B – C – C# – D – D# – E – F – F# – G – G# – A
Rarely ever are compositions or songs based solely off a chromatic scale more often the chromatic scale is laced in a composition or song using a diatonic scale.