The quantum mechanical model of the atom describes the behavior of electrons in terms of probabilities rather than fixed orbits. In this model, electrons exist in regions called orbitals, which are defined by specific energy levels. This approach accounts for the wave-particle duality of electrons, meaning they exhibit both particle-like and wave-like properties. Developed in the early 20th century, this model builds on the work of scientists like Niels Bohr and Erwin Schrödinger. It emphasizes that we can only predict the likelihood of finding an electron in a particular location, rather than pinpointing its exact position at any given time.