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Chapter 7

Chapter 7. Electronic Structure of Atoms. The Wave Nature of Light. The electronic structure of an atom refers to the arrangement of the electrons. Visible light is a form of Electromagnetic radiation (EMR). Radiation carries energy through space EMR is characterized by its wave.

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Chapter 7

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  1. Chapter 7 Electronic Structure of Atoms

  2. The Wave Nature of Light • The electronic structure of an atom refers to the arrangement of the electrons. • Visible light is a form of Electromagnetic radiation (EMR). • Radiation carries energy through space • EMR is characterized by its wave

  3. Wave Properties • All waves have a characteristic wavelength, λ (lambda), and amplitude, A. • The frequency, ν (nu), of a wave is the number of cycles which pass a point in one second. • The units of ν are Hertz. (1Hz = 1/s)

  4. The speed of a wave is determined by its frequency multiplied by its wavelength. • The speed of EMR is always the same no matter what the wavelength or frequency. • The speed of EMR is equal to the speed of light. The symbol for the speed of light is “c”. • The numerical value for c is a constant and is always equal to 3.0 x 10 8 m/s

  5. Since the speed of the wave is constant, if the frequency is known, the wavelength can be determined. • Likewise, if the wavelength is known, the frequency can be determined. • Frequency and wavelength are inversely related.

  6. The relationship between frequency (ν ) and wavelength (λ )is shown by the equation c = λ ν Where c = the speed of light = 3.0 x 108m/s λ = the wavelength of the wave ν = the frequency of the wave

  7. Light as Electricity and Magnetism • Max Planck determined mathematically that light is both magnetism and electricity. • He determined the Energy in a photon is directly related to its frequency . If the frequency is multiplied by Planck’s constant (6.6261 x 10-34 J-s), the Energy of the photon can be determined. • This relationship is represented in the formula E=h ν • Where E is Energy • H is Planck’s constant = (6.6261 x 10-34 J-s) • ν = frequency

  8. Schroedinger’sQUANTUM MECHANICAL MODEL OF THE ATOM • The quantum mechanical model is a way of describing the atom through electron movement. • Electrons are arranged in orbitals around the nucleus. • If the electrons gain a photon (specific amount) of energy they can travel to higher energy levels. • The energy level the electron travels to will be determined by the amount of energy in the photon. • The electron cannot maintain this higher energy level and eventually returns to a lower level. • The eneregy is released as it travels down in the form of emr. • The color you see depends on the wavelength of the light released.

  9. Determining the Energy of the photon. • To determine the Energy of the photon released, we use the formula E=h ν

  10. Example: • PROBLEM: What is the energy of a photon with a frequency of 3.7 x 107Hz? • SOLUTION: Use the formula E=h ν. E = ? h= 6.6261 x 10-34 J-s ν = 3.7 x 107Hz E= (6.6261 x 10-34 J-s ) (3.7 x 1071/s)= 24.51657 x 1027 J Then 24.51657 is not a number between 1 and 10. 2.451657 x 10 28 J

  11. Problem: What is thefrequency of a photon with Energy

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