Atomic Structure

About this lesson

This unit covers the historical development of atomic structure models, starting with Thomson's solid sphere model, then Rutherford's nuclear model based on the gold foil experiment, and Bohr's model with quantized energy levels. It explains atomic emission spectra and how Bohr's model explained hydrogen's spectrum but failed for other elements. The unit then introduces modern atomic theory, including the dual nature of electrons, Heisenberg's uncertainty principle, and Schrödinger's wave mechanical theory, leading to the concepts of electron clouds and orbitals. It details the four quantum numbers (principal, subsidiary, magnetic, and spin) and their roles in describing electron location and behavior. Finally, it presents the principles of electron configuration: Pauli's exclusion principle, the Aufbau principle, and Hund's rule, with examples of writing configurations for various atoms. By the end, students should be able to describe each atomic model, explain their limitations, define electron cloud and orbital, identify quantum numbers, relate principal quantum number to sublevels and orbitals, and apply electron configuration rules.