What does atonal harmony lack?

Atonal harmony is characterized primarily by the absence of a tonal center, which means it does not establish a key or a central pitch around which melodies and harmonies are organized. In traditional tonal music, there is a strong sense of gravity towards a home note or tonic, which serves as the foundation for harmonic and melodic relationships. However, in atonal music, this tonal center is intentionally avoided, leading to an equal treatment of all tones and creating a soundscape that lacks the familiar pull and resolution associated with tonal music.

While atonal music can definitely have melodies, rhythmic structures, and various forms of harmonic progressions, the defining feature that sets it apart is indeed the absence of any central pitch around which the rest of the music revolves. This creates a distinct listening experience that can be perceived as more abstract or complex. As a result, the lack of a tonal center is what truly defines atonal harmony.