The quantum mechanical model Warm up: Sketch the model of the atom throughout history Dalton’s Atomic Model Plum Pudding Model (Thomson) Bohr’s Model Quantum Mechanical Model • 1920’s • Werner Heisenberg (Uncertainty Principle) • Louis de Broglie (electron has wave properes) • Erwin Schrodinger (mathemacal equaons using probability, quantum numbers) Werner Heisenberg: Uncertainty Principle • We can not know both the posiMon and momentum of a parMcle at a given Mme. Balloon in a dark room Louis de Broglie, (France, 1892-1987) Wave ProperMes of Maer (1923) •Since light waves have a parMcle behavior (as shown by Einstein in the Photoelectric Effect), then parMcles could have a wave behavior. •de Broglie wavelength λ= h mv Electron MoMon Around Atom Shown as a de Broglie Wave Erwin Schrodinger, 1925 Quantum (wave) Mechanical Model of the Atom • Derived an equaon that treated the electron as a wave • Was successful in describing the electrons in all atoms – not just the one electron in hydrogen as in the Bohr model Schrodinger’s wave funcMon The quantum mechanical model predicts a three dimensional region around the nucleus, where the electron is likely found, called the atomic orbital Atomic Orbital • Region in space where there is a high probability of finding an electron Atomic Orbital s 2s Degenerate Orbitals • Equal energy orbitals • Oriented differently in space Example of degenerate orbitals: p orbitals hUp://www.rmutphysics.com/CHARUD/scibook/crystal-structure/porbital.gif • The d orbitals f orbitals The Electron Cloud • The electron cloud represents posiMons where there is probability of finding an electron. The Electron Cloud The higher the electron density, the higher the probability that an electron may be found in that region. The Electron Cloud for Hydrogen 90% probability of finding the electron within this space Probability Curve for Hydrogen FYI: Schrodinger’s Equaon • ψ is called the wave function and indicates the probability of where an electron may be found. Summary: Quantum Mechanical Model • Electrons are located in specific energy levels. • There is no exact path around the nucleus. • The model esMmates the probability of finding an electron in a certain posiMon. Homework • Create a table comparing and contrasMng the Bohr model with the Quantum Mechanical Model • Read “Tiny Tweezers” on p. 163 for an applicaon of light interacMng with maer Bohr Model Quantum Mechanical Model .