* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download I. Waves & Particles
Topological quantum field theory wikipedia , lookup
Casimir effect wikipedia , lookup
Probability amplitude wikipedia , lookup
Path integral formulation wikipedia , lookup
Renormalization group wikipedia , lookup
Delayed choice quantum eraser wikipedia , lookup
Quantum entanglement wikipedia , lookup
Quantum dot wikipedia , lookup
Scalar field theory wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Quantum fiction wikipedia , lookup
Quantum field theory wikipedia , lookup
Coherent states wikipedia , lookup
Quantum computing wikipedia , lookup
Bell's theorem wikipedia , lookup
Many-worlds interpretation wikipedia , lookup
Renormalization wikipedia , lookup
Relativistic quantum mechanics wikipedia , lookup
Copenhagen interpretation wikipedia , lookup
Quantum teleportation wikipedia , lookup
Quantum machine learning wikipedia , lookup
Orchestrated objective reduction wikipedia , lookup
Particle in a box wikipedia , lookup
Double-slit experiment wikipedia , lookup
Quantum group wikipedia , lookup
Atomic theory wikipedia , lookup
Interpretations of quantum mechanics wikipedia , lookup
Quantum electrodynamics wikipedia , lookup
Atomic orbital wikipedia , lookup
Bohr–Einstein debates wikipedia , lookup
Quantum key distribution wikipedia , lookup
Symmetry in quantum mechanics wikipedia , lookup
Electron configuration wikipedia , lookup
Quantum state wikipedia , lookup
Matter wave wikipedia , lookup
EPR paradox wikipedia , lookup
Canonical quantization wikipedia , lookup
History of quantum field theory wikipedia , lookup
Hydrogen atom wikipedia , lookup
Hidden variable theory wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Ch. 6 – Electronic Structure of Atoms I. Waves & Particles Properties of Waves Many of the properties of light may be described in terms of waves even though light also has particle-like characteristics. Waves are repetitive in nature A. Waves Wavelength () - length of one complete wave; units of m or nm Frequency () - # of waves that pass a point during a certain time period hertz (Hz) = 1/s Amplitude (A) - distance from the origin to the trough or crest A. Waves crest A greater amplitude origin (intensity) A trough greater frequency (color) Electromagnetic Radiation Electromagnetic radiation: (def) form of energy that exhibits wavelike behavior as it travels through space Types of electromagnetic radiation: visible light, x-rays, ultraviolet (UV), infrared (IR), radiowaves, microwaves, gamma rays Electromagnetic Spectrum All forms of electromagnetic radiation move at a speed of about 3.0 x 108 m/s through a vacuum (speed of light) Electromagnetic spectrum: made of all the forms of electromagnetic radiation B. EM Spectrum H I G H E N E R G Y L O W E N E R G Y B. EM Spectrum H I G H L O W E N E R G Y red R O Y G. orange green yellow B blue I indigo V violet E N E R G Y B. EM Spectrum Frequency & wavelength are inversely proportional c = c: speed of light (3.00 108 m/s) : wavelength (m, nm, etc.) : frequency (Hz) B. EM Spectrum EX: Find the frequency of a photon with a wavelength of 434 nm. GIVEN: WORK: =c =? = 434 nm = 4.34 10-7 m = 3.00 108 m/s -7 m 8 4.34 10 c = 3.00 10 m/s = 6.91 1014 Hz C. Quantum Theory Photoelectric effect: emission of electrons from a metal when light shines on the metal Hmm… (For a given metal, no electrons were emitted if the light’s frequency was below a certain minimum – why did light have to be of a minimum frequency?) C. Quantum Theory Planck (1900) Observed - emission of light from hot objects Concluded - energy is emitted in small, specific amounts (quanta) Quantum - minimum amount of energy change C. Quantum Theory Planck (1900) vs. Classical Theory Quantum Theory C. Quantum Theory Einstein (1905) Observed - photoelectric effect C. Quantum Theory The energy of a photon is proportional to its frequency. E = h E: energy (J, joules) h: Planck’s constant (6.626 10-34 J·s) : frequency (Hz) C. Quantum Theory EX: Find the energy of a red photon with a frequency of 4.57 1014 Hz. GIVEN: WORK: E=? E = h = 4.57 1014 Hz E = (6.6262 10-34 J·s) h = 6.6262 10-34 J·s (4.57 1014 Hz) E = 3.03 10-19 J C. Quantum Theory Einstein (1905) Concluded - light has properties of both waves and particles “wave-particle duality” Photon - particle of light that carries a quantum of energy Ch.66.3. Bohr Model of the Atom Excited and Ground State Ground state: lowest energy state of an atom Excited state: an atom has a higher potential energy than it had in its ground state When an excited atom returns to its ground state, it gives off the energy it gained as EM radiation A. Line-Emission Spectrum excited state ENERGY IN PHOTON OUT ground state B. Bohr Model 2) e- exist only in orbits with specific amounts of energy called energy levels When e- are in these orbitals, they have fixed energy Energy of e- are higher when they are further from the nucleus B. Bohr Model Therefore…Bohr model leads us to conclude that: e- can only gain or lose certain amounts of energy only certain photons are produced B. Bohr Model 65 4 3 2 1 Energy of photon depends on the difference in energy levels Bohr’s calculated energies matched the IR, visible, and UV lines for the H atom Each element has a unique bright-line emission spectrum. “Atomic Fingerprint” Helium Bohr’s calculations only worked for hydrogen! Ch. 6 - Electrons in Atoms III. Wave Behavior of Matter A. Electrons as Waves Louis de Broglie (1924) Applied wave-particle theory to ee- exhibit wave properties QUANTIZED WAVELENGTHS A. Electrons as Waves EVIDENCE: DIFFRACTION PATTERNS VISIBLE LIGHT ELECTRONS A. Electrons as Waves Diffraction: (def) bending of a wave as it passes by the edge of an object Interference: (def) when waves overlap (causes reduction and increase in energy in some areas of waves) Chapter 6 6.5: Quantum Model A. Quantum Mechanics Heisenberg Uncertainty Principle Impossible to know both the velocity and position of an electron A. Quantum Mechanics Schrödinger Wave Equation (1926) finite # of solutions quantized energy levels defines probability of finding an e- Ψ 1s 1 Z 3/2 σ π a0 e B . Quantum Mechanics Schrodinger wave equation and Heisenberg Uncertainty Principle laid foundation for modern quantum theory Quantum theory: (def) describes mathematically the wave properties of e- and other very small particles B. Quantum Mechanics Orbital (“electron cloud”) Region in space where there is 90% probability of finding an e- Orbital Radial Distribution Curve C. Quantum Numbers Four Quantum Numbers: Specify the “address” of each electron in an atom UPPER LEVEL C. Quantum Numbers 1. Principal Quantum Number ( n ) Main energy level Size of the orbital n2 = # of orbitals in the energy level C. Quantum Numbers 2. Angular Momentum Quantum # ( l ) Energy sublevel Shape of the orbital (# of possible shapes equal to n) values from 0 to n-1 s p d f C. Quantum Numbers If l equals… Then orbital shape is… 0 s 1 p 2 d 3 f Principle quantum # followed by letter of sublevel designates an atomic orbital C. Quantum Numbers 3. Magnetic Quantum Number ( ml ) Orientation of orbital Specifies the exact orbital within each sublevel C. Quantum Numbers Values for ml: m = -l… 0… +l C. Quantum Numbers px py pz C. Quantum Numbers Orbitals combine to form a spherical shape. 2px 2py 2s 2pz C. Quantum Numbers 4. Spin Quantum Number ( ms ) Electron spin +½ or -½ An orbital can hold 2 electrons that spin in opposite directions. C. Quantum Numbers Pauli Exclusion Principle No two electrons in an atom can have the same 4 quantum numbers. Each e- has a unique “address”: 1. Principal # 2. Ang. Mom. # 3. Magnetic # 4. Spin # energy level sublevel (s,p,d,f) orbital electron C. Quantum Numbers n = # of sublevels per level n2 = # of orbitals per level Sublevel sets: 1 s, 3 p, 5 d, 7 f Wrap-Up Quantum # Symbol What it describes Principle n main E level, quantum # size of orbital Possible values n = positive whole integers Angular Momentum Quantum # l sublevels and their shapes 0 to (n-1) Magnetic Quantum # Spin Quantum # ml orientation of orbital electron spin -l … 0 … +l ms +1/2 or -1/2 Feeling overwhelmed? Read Section 4-2!