How did Arnold Schoenberg’s use of all 12 chromatic tones remove a single tonal center?

Arnold Schoenberg removed a single tonal center by replacing the traditional hierarchical system of tonality—which focuses on a tonic or key center—with a method where all 12 tones of the chromatic scale are "related only to one another."12

In traditional tonal music, specific pitches or chords serve as focal points that create a sense of movement toward or away from a central key. Schoenberg felt this system was being distorted by excessive chromaticism and sought a new structural basis. By utilizing all 12 tones, he ensured that no single note would predominate as a focal point or hold a higher level of importance than others.21

To organize this system, Schoenberg developed 12-tone music, in which a composer arranges the 12 pitches into an ordered sequence known as a tone row or basic set. This row provides a framework for the composition, allowing the pitches to function independently of a traditional key. This approach, a form of serialism, effectively eliminated the reliance on functional harmony based on diatonic scales.123