Chemistry Quantum Atomic Theory Part 1 PDF

Chapter Outline 7.1 Quantum Mechanics: The Theory That Explains the Behaviour of the Absolutely Small 7.2 The Nature of Light 7.3 Atomic Spectroscopy and the Bohr Model 7.4 The Wave Nature of Matter: The de Broglie Wavelength, the Uncertainty Principle, and Indeterminacy – skip, covered...

Chapter Outline 7.1 Quantum Mechanics: The Theory That Explains the Behaviour of the Absolutely Small 7.2 The Nature of Light 7.3 Atomic Spectroscopy and the Bohr Model 7.4 The Wave Nature of Matter: The de Broglie Wavelength, the Uncertainty Principle, and Indeterminacy – skip, covered in PHY 301/CH 382 7.5 Quantum Mechanics - skip and Electrons in Atoms 7.6 The Shapes of Atomic Orbitals 7.7 Electron Configurations: How Electrons Occupy Orbitals Copyright © 2023 Pearson Canada Inc. 7-1 7.1 Quantum Mechanics: The Theory That Explains the Behaviour of the Absolutely Small The quantum-mechanical model of the atom A model that explains how electrons exist in atoms and how those electrons determine the chemical and physical properties of elements. Quantum – a discreet unit, packet of something Copyright © 2023 Pearson Canada Inc. 7-2 The Wace Nature of Light Wave has two components – an electric field component and a magnetic field component Light travels through space as a wave, similar to an ocean wave Oscillating, mutually perpendicular electric and magnetic fields. The speed is 2.998 x 108 m/s, enough to circle the Earth in one-seventh of a second. Figure 7.1 Electromagnetic Radiation Copyright © 2023 Pearson Canada Inc. 7-3 The Wave Nature of Light (1 of 4) What do you see/hear first? Hear a thunder and see the lightning? How do you know how far the lightning strikes? Because light travels nearly a million times faster than sound, the flash of lightning reaches your eyes before the roll of thunder reaches your ears. Copyright © 2023 Pearson Canada Inc. 7-4 How far from me did the lightning strike? Survival You see the lightning – count the time between that and when you hear the thunder. Since speed = distance/time (you probably learned that in basic physics), distance = speed x time 340 m/s x elapsed time (seconds) = distance from the striking location That estimates the distance of the point of lightning. Copyright © 2023 Pearson Canada Inc. 7-5  The Wave Nature of Light (2 of 4) Wavelength (λ) is the distance the light wave travels in one cycle (peak to peak) basic unit: m Frequency (ν) is the number of wave cycles completed in each second. Basic unit: s-1 or Hz Copyright © 2023 Pearson Canada Inc. 7-6 The Wave Nature of Light (3 of 4) c v= c = λv λ Figure 7.2 Wavelength and Amplitude Copyright © 2023 Pearson Canada Inc. 7-7 Example Calculate the wavelength (in nm) of the red light emitted by a barcode scanner that has a frequency of 4.62×1014 s−1. 1 nm = 10-9 m Copyright © 2023 Pearson Canada Inc. 7-8 The Wave Nature of Light (4 of 4) Figure 7.3 Components of White Light Figure 7.4 The Colour of an Object [Richard Griffin/Fotolia] [Uluc Ceylani/Shutterstock] Copyright © 2023 Pearson Canada Inc. 7-9  The Electromagnetic Spectrum The complete radiant energy spectrum is an uninterrupted band, or continuous spectrum. The radiant energy spectrum includes many types of radiation, most of which are invisible to the human eye (radio, IR, UV, X-ray, etc). Figure 7.5 The Electromagnetic Spectrum Copyright © 2023 Pearson Canada Inc. 7 - 10 The Particle Nature of Light (1 of 4) Figure 7.8 The Photoelectric Effect Copyright © 2023 Pearson Canada Inc. 7 - 11 Photoelectric Effect – the Particle Nature of Light An experiment in which light was shone on a metal surface in a vacuum-sealed container If the energy applied to the metal was high enough, it was observed on the detector that some electrons were ejected from the metal We are able to calculate the energy of light. Copyright © 2023 Pearson Canada Inc. 7 - 12 The Particle Nature of Light (3 of 4) Max Planck: light energy must come in packets E = hv 7.2 h – Planck’s constant = 6.626 x 10-34 J s Copyright © 2023 Pearson Canada Inc. 7 - 13 The Particle Nature of Light (4 of 4) Einstein: explained photoelectric effect using Planck’s idea. hc E = hv E= 7.4  No individual photon has sufficient energy to eject an electron until a threshold energy of binding is exceeded by the photon energy packet. Photon – smallest packet of light Copyright © 2023 Pearson Canada Inc. 7 - 14 Example Calculate the energy of a photon of electromagnetic radiation: at a frequency of 1070 kHz (typical frequency for AM radio broadcasting) of wavelength of 0.052 nm (a wavelength contained in medical X-rays) Copyright © 2023 Pearson Canada Inc. 7 - 15 7.3 Atomic Spectroscopy and the Bohr Model exciting elements with energy causes emission of light depending on the type of element, a different color will be observed Figure 7.10 Mercury, Helium, and Hydrogen [Pearson Education] Copyright © 2023 Pearson Canada Inc. 7 - 16 Atomic Spectroscopy When an electrical voltage is passed across a gas in a sealed tube and through a prism, a series of narrow lines is seen. These lines are the emission line spectrum. The emission line spectrum for hydrogen gas shows three lines in the visible region. This experiment applied to any element shows an emission line spectrum which is unique to each element – atomic fingerprints. Niels Bohr realized this is to prove his theory about atomic orbitals. Figure 7.11 Emission Spectra Copyright © 2023 Pearson Canada Inc. 7 - 17 Copyright © 2023 Pearson Canada Inc. 7 - 18 The Quantum Concept The quantum concept states that energy is present in small, discrete bundles. Copyright © 2023 Pearson Canada Inc. 7 - 19 The Bohr Model Niels Bohr speculated that electrons orbit about the nucleus in fixed energy levels. Electrons are found only in specific energy levels, and nowhere else. The electron energy levels are quantized. Copyright © 2023 Pearson Canada Inc. 7 - 20 The Bohr Model Figure 7.12 The Bohr Model and Emission Spectra Copyright © 2023 Pearson Canada Inc. 7 - 21 Bohr model and emission spectrum Bohr realized that the hydrogen lamp spectrum was the evidence he needed to prove his theory. The electric charge temporarily excites an electron to a higher orbit. When the electron drops back down, a photon is given off. The red line is the least energetic and corresponds to an electron dropping from energy level 3 to energy level 2. Copyright © 2023 Pearson Canada Inc. 7 - 22 Atomic Spectra Explained (1 of 4)  1 En = − 2.18 10 −18 J  2  n = 1, 2,3,. [7.6] n  Figure 7.13 Excitation and Radiation Copyright © 2023 Pearson Canada Inc. 7 - 23 Atomic Spectra Explained (2 of 4)  1  En = −2.18  10−18 J  2  7.6 n  E = E final − Einitial  1   1  E = Enf − Eni = −2.18  10 −18 J  2  nf  −  2   7.7    ni   Copyright © 2023 Pearson Canada Inc. 7 - 24 Atomic Spectra Explained (3 of 4) Figure 7.17 Hydrogen Energy Transitions and Radiation Copyright © 2023 Pearson Canada Inc. 7 - 25 Atomic Spectra Explained (4 of 4) Bohr theory was successful in explaining the spectra of hydrogen like ions (such as He+, Li2+, Mg3+)  1   1  E = Enf − Eni = −2.18  10 −18 J  Ζ  2 2  nf  −  2   7.8    ni   Where Z is the atomic number (nuclear charge). Copyright © 2023 Pearson Canada Inc. 7 - 26 Quantum numbers They are used to describe the position and type of electron Principal quantum number: n Angular momentum quantum number: l Magnetic quantum number: ml Copyright © 2023 Pearson Canada Inc. 7 - 27