The document discusses different models of the atom, including Bohr's model, the quantum mechanical model, and atomic orbitals. Bohr's model describes electrons orbiting the nucleus in specific energy levels. The quantum mechanical model describes electron location and energy in terms of probability. Atomic orbitals describe the possible shapes and locations of electrons, which are labeled by principal quantum numbers and include 1s, 2s, 2p, and higher orbitals. Electron configuration shows the ordering of electrons filling these orbitals based on energy levels and rules such as the Aufbau principle and Pauli exclusion principle.