According to quantum field theory (QFT), the electron inside an atom is described as a quantum field that permeates all of space and time. The behavior of this quantum field can be described as a particle-like entity called an electron, but it also exhibits wave-like characteristics.
In QFT, particles are understood as excitations or quanta of their corresponding quantum fields. The electron field extends throughout space and interacts with other fields, such as the electromagnetic field. When an interaction occurs, the electron field can be "excited" or "perturbed," resulting in the creation or annihilation of an electron particle.
The behavior of the electron field is described by a wave function, which is a mathematical expression that captures the probabilities of various outcomes when measuring certain properties of the electron. The wave function incorporates both particle-like and wave-like aspects of the electron. It provides information about the distribution of the electron's position, momentum, and other observable quantities.
When an electron interacts with other particles or fields, its wave function can undergo changes, such as superposition and interference, similar to the behavior of waves. This wave-like behavior is observed in phenomena like electron diffraction and interference experiments.
It's important to note that the concept of "wave-particle duality" arises from the mathematical formalism of quantum mechanics, which includes QFT. The electron is neither strictly a classical particle nor a classical wave but exhibits characteristics of both depending on the context and the type of observation or measurement being made.
In summary, according to QFT, the electron inside an atom is described as a quantum field that can be interpreted as a particle-like entity. Its behavior is described by a wave function, which incorporates both particle-like and wave-like aspects. The electron exhibits wave-like behavior in certain experiments, while its particle-like nature is observed in interactions and measurements.