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Transcript

Wave-Particle Duality Electronic structure (electron configurations) - base for many chemistry concepts. ex: molecular geometry & chemical reactivity. Electromagnetic radiation is the probe used to obtain knowledge of the electronic structure. Electromagnetic Radiation Short Wavelength =High Frequency = High ENERGY Long Wavelength = Low Frequency = Low ENERGY Electromagnetic radiation propagates through space as a wave moving at the speed of light. WAVE MODEL c = C = speed of light (3.00 x 108 m/s) = wavelength, (m); distance between 2 peaks = frequency, (hertz = hz, sec-1); # peaks per time INVERSE Is this a direct or inverse relationship? ___________ Direct = DDSS Direct, Divide, Same variable direction, Straight line What is the speed at which radio waves travel? 3 x 108 m/s Which one travels faster red or blue light? Same Speed = 3 x 108 m/s Which has more energy red or blue light? BLUE = higher frequency Constructive Interference Waves - SYNCHRONIZED -ENLARGED wave result bright bands Destructive Interference Waves -NOT SYNCHRONIZED - waves cancel out result black/gray bands De Broglie’s Equation • Broglie’s stated that an object in motion behaves as both particles & waves, just as light does. • Electrons are WAVES in FIXED LOCATIONS which means they are QUANTIZED (quantity) wavelengths. Sizes of s orbitals Orbitals of the same shape grow larger as n increases… Nodes are regions of low probability within an orbital. Heisenberg Uncertainty Principle “One cannot simultaneously determine both the position and momentum of an electron. Schrodinger (CAT) Wave Equation d h 8 m dx 2 2 2 2 V E Equation for probability of a single electron being found along a single axis (x-axis) Schrodinger wave equation & Heisenberg Uncertainty principle provided the framework for the QUANTUM THEORY! Realized hot object do NOT emit electromagnetic energy continuously but as energy in small specific amounts called quanta (wave) Particle Model (Planck’s Equation) Ephoton= h E photon= Energy (Joules = kg·m2/s2) h = Planck’s constant (6.626 x 10-34 J·s) = frequency (hertz = hz, sec-1) Energy is directly related to FREQUENCY. What is photon? – particle of light ABSORPTION Ground State Excited State EMISSION Camp Fire Hot Metal Spectroscopic analysis : wavelength analysis Continuous Emission Spectrum: produces all colors Bright Line emission spectrum: produce specific wavelengths ** Wavelength analysis is a FINGERPRINT for element. SUMMARY Wave Theory Formula: c = Measurable characteristics - Frequency & wavelength Light can interfere and diffract (bend) Particle Theory Formula E = h Light when it absorbs/emits by matter 1) photoelectric effect (shiny metal) 2) Absorption of Light by HOT objects 3) Line-Emission Spectra of elements Light has mass!! Light is a particle!! It both a wave-particle called PHOTON (zero mass carrying a quantum of energy) Einstein’s Equation E = mc2 CoMbInInG FoRmUlA’s Wave Equation: c = = c/ = c/ inserted into Planck’s (Particle) Equation E = h E = (hc)/ Einstein’s Equation E = mc2 Combine (hc)/ = mc2 (hc) = mc2 = (hc) / (mc2) = h/mc or …”c” cancels out….. m = h/ c note: c = speed = velocity What does this MEAN? Anything that has both MASS and VELOCITY (movement) has a corresponding WAVELENGTH! Observed Spectra of Elements Wave-Particle Duality JJ Thomson won the Nobel prize for describing the electron as a particle. The electron is a particle! The electron is an energy wave! George Thomson won the Nobel prize for describing the wave-like nature of the electron.