1. Bohr Model: This model, proposed by Niels Bohr in 1913, is a simplified model that depicts electrons orbiting the nucleus in fixed, circular paths called orbits. It's a helpful way to visualize electron behavior, but it has limitations as it doesn't fully explain the complex quantum nature of electrons.
2. Quantum Mechanical Model: This is the more accurate and complex model. It describes electrons not as orbiting particles but as probability distributions within regions called orbitals. These orbitals are three-dimensional spaces where there's a high probability of finding an electron. This model is based on the idea that electrons have wave-like properties and their exact location can't be determined precisely.
So, the answer is: Scientists primarily use the quantum mechanical model to talk about the behavior of electrons in atoms. However, they might also use the Bohr model as a simplified way to visualize the concept of electron orbits, especially in introductory discussions.
