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Why are electron orbitals described as probability regions rather than fixed paths?

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Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

In the context of atomic structure, electron orbitals are described as probability regions rather than fixed paths because of the fundamental principles of quantum mechanics.1

Early models, such as the Bohr atomic model, incorrectly visualized electrons as point particles moving in defined, planetary-like orbits. However, quantum mechanics reveals that electrons exhibit wave-particle duality. Because of this, an electron cannot be localized to a precise path; instead, it is represented by a mathematical expression known as a wave function.123

The Heisenberg uncertainty principle further dictates that it is impossible to simultaneously know an electron's exact position and momentum. Consequently, an orbital is defined not as a trajectory, but as a three-dimensional region in space where there is a high probability (typically 95 percent) of finding the electron. Rather than a point particle orbiting a nucleus, the electron is more accurately viewed as being spread out in a quantum "fuzz ball" of probability.234