Template:HideTOC 9.1: Blimps, Balloons, and Models of the Atom 9.2: Light is Visible Electromagnetic Radiation Light acts like a wave, with a frequency and a wavelength. The frequency and wavelength of light are related by the speed of light, a constant. Light acts like a particle of energy, whose value is related to the frequency of light. c = \lambda \nu 9.3: The Electromagnetic Spectrum Electromagnetic waves have an extremely wide range of wavelengths, frequencies, and energies. The highest energy form of electromagnetic waves are gamma (γ) rays and the lowest energy form are radio waves. 9.4: The Bohr Model - Atoms with Orbits Bohr's model suggests each atom has a set of unchangeable energy levels and electrons in the electron cloud of that atom must be in one of those energy levels. Bohr's model suggests that the atomic spectra of atoms is produced by electrons gaining energy from some source, jumping up to a higher energy level, then immediately dropping back to a lower energy level and emitting the energy different between the two energy levels. The existence of the atomic spectra is support for Bohr's model, 9.5: The Quantum-Mechanical Model- Atoms with Orbitals Quantum mechanics involves the study of material at the atomic level. This field deals with probabilities since we cannot definitely locate a particle. Orbitals are mathematically derived regions of space with different probabilities of having an electron. 9.6: Quantum-Mechanical Orbitals and Electron Configurations We look at the four quantum numbers for a given electron. Electron configuration notation simplifies the indication of where electrons are located in a specific atom. The Aufbau principle gives the order of electron filling in an atom. Hund's rule specifies the order of electron filling within a set of orbitals. Orbital filling diagrams are a way of indicating electron locations in orbitals. 9.7: Electron Configurations and the Periodic Table The arrangement of electrons in atoms is responsible for the shape of the periodic table. Electron configurations can be predicted by the position of an atom on the periodic table. 9.8: The Explanatory Power of the Quantum-Mechanical Model The chemical properties of elements is determined primarily by the number and distribution of valence electrons. 9.9: Periodic Trends - Atomic Size, Ionization Energy, and Metallic Character Certain properties—notably atomic radius, ionization energy, electron affinity and metallic character—can be qualitatively understood by the positions of the elements on the periodic table. 9.E: Electrons in Atoms and the Periodic Table (Exercises) Template:HideTOC