CH2 [Compatibility Mode]

CH2 [Compatibility Mode] - Chapter 2: What is Quantum...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 2: Classical Physics is unable to describe: objects going very fast Relativity objects that are very small Quantum Mechanics What is Quantum Mechanics? • Mathematical Theory • “describes the behavior of objects that are roughly 10,000,000,000 times smaller than a typical human being.” http://rugth30.phys.rug.nl/quantummechanics/ Key Concepts: Quantization Wave-Particle Duality Probability Uncertainty Early model of the atom Nucleus: protons + neutrons Orbiting e - ’s Rutherford model of the atom Much of what we know about matter is based on the way electrons interact with L I G H T . Light is a form of energy Electron + light = higher energy electron Electron – light = lower energy electron Section 2.1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Electromagnetic spectrum Light exists as a wave Waves have repeat lengths, frequencies and intensities. Long wavelength Short Wavelength Wavelength = λ Section 2.1 Frequency All light waves travel at the same speed, the speed of light (c) 2.998x10 8 ms -1 frequency ( ν ) = # waves/sec (s -1 ) Section 2.1 Long Wavelength Low Frequency LOW ENERGY Short Wavelength High Frequency HIGH ENERGY Wavelength and Frequency c = λ ν c is the speed of light (2.9x10 8 m/s) λ is wavelength (m) ν is frequency (s -1 or hertz) Section 2.1 constant! So, if you know wavelength, you know frequency and vice versa!
Background image of page 2
3 Electromagnetic spectrum Which of the following wavelengths of light has the lowest frequency? 1. 240 nm 2. 500 nm 1234 0% 0% 0% 0% 10 3. 1200 nm 4. 2400 nm Is light a wave or a particle? Classical Experiments: Light is a wave c = λ ν Planck and Einstein: Light energy is quantized and is composed of massless 'particles' called photons Wave - particle Duality of light h = Planck's constant 6.626x10 -34 J·s , c=speed of light photon one of energy hc h E = = = λ ν Which of the following wavelengths of light has the highest energy? 1. 240 nm 2. 500 nm 0% 0% 0% 0% 10 3. 1200 nm 4. 2400 nm
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 What is the wavelength in nanometers, of light with energy of 5.2x10 -19 J? 25% 25% 25% 25% 1. 3.7x10 -7 nm 2. 370 nm 3. 1.0x10 -43 nm 1234 10 4. 1200 nm Atomic Spectra: Light Absorption and Emission Line spectrum of hydrogen gas Violet λ = 410 nm Blue λ = 434 nm Blue-green λ = 486 nm Red λ = 656 nm Neon Signs (~ 1870) Line Spectrum from a Hydrogen Discharge Tube Law of Conservation of Energy Energy cannot be created nor destroyed. Conclusion: The energy of the emitted photon (h ν ) must come from an energy change within the atom, Δ E atom E photon Δ E atom = Conclusion: Since the energy of the emitted photons is quantized, the energy of the atom is quantized. ..
Background image of page 4
5 The Bohr Model of the Hydrogen Atom •Bohr introduced quantum theory into the atomic model •The electron can circle the nucleus in orbits of only certain radii corresponding to specific energies Energy of the electron is quantized hR=2.180x10 -18 J Z=atomic number n=principal quantum number = 2 2 n Z hR E n lo hi n n atom E E E = Δ n lo < n hi
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 14

CH2 [Compatibility Mode] - Chapter 2: What is Quantum...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online