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Since matter is discontinuous and particulate, maybe energy is discontinuous and particulate: a. Planck: Blackbody radiation b. Einstein: photoelectric effect c. Bohr: Atomic line spectra Planck: energy is quantized -- only certain values allowed called "black" because no color is actually reflected Einstein: Light has particulate behavior (photons) photoelectric effect Bohr: energy of atoms is quantized photons are emitted or absorbed when an electron changes orbit Since energy is wavelike, perhaps MATTER is wavelike. de Broglie: all matter travels in waves: energy of atoms is quantized due to wave motion of electrons Davisson/Germer: electron beam is diffracted by metal crystal Since matter has mass, perhaps energy has mass. Einstein/de Broglie: mass and energy are equal. Particles have wavelength and photons have momentum. Compton: photon's wavelength increases (momentum decreases) after colliding with electron. QUANTUM THEORY Energy and matter are particulate, massive and wavelike What is a quantum? a discrete quantity of energy proportional to the frequency of the radiation emitted Rydberg equation R = 1.097 x 107m-1 n1 = lower energy level n2 = higher energy level En = -RH(1/n2) What does it solve? The Rydberg equation is a mathematical formula used to predict the wavelength of light resulting from an electron moving between energy levels of an atom. Bohr model: assumptions limitations Flame test Heisenberg uncertainty principle: cannot simultaneously know the exact location or momentum of an electron Schrodinger * wrote an equation that treated the electron as a wave. * equation gives a wave function for the electron - mathematical description of where the electron can be, but says nothing at all about where it actually is. * Orbitals are squarres of the wave function. * There are three quantum numbers that describe what the orbital looks like: n, l and m electron density Radial probability distribution plot Atomic orbitals