The Quantum Mechanical Model of the Atom

1. The Quantum Mechanical Model of the Atom • Outline • Light • Atomic Spectra • Bohr’s Model of the Atom • Wave-Particle Duality • de Broglie Wavelength • Uncertainty Principle • Quantum Mechanical Atom • Schrodinger Equation • Quantum Numbers, n, l, ml, ms • Orbitals Chapter 7

4. Can you see interference patterns generated by the diffraction of light between your fingers?

6. Wave - A vibrational disturbance which transmits energy.

8. Chapter 7: Examples – EMR Radioastronomers use 1,420 MHz waves to look at interstellar clouds of hydrogen atoms. • What is the wavelength of this radiation? • What is the wavenumber?

9. low frequency and energy high frequency and energy Types of Electromagnetic Radiation • Electromagnetic waves are classified by their wavelength • Radiowaves = l > 0.01 m • Microwaves = 10−4 < l < 10−2 m • Infrared (IR) • far = 10−5 < l < 10−4 m • middle = 2 x 10−6 < l < 10−5 m • near = 8 x 10−7< l < 2 x 10−6m • Visible = 4 x 10−7 < l < 8 x 10−7 m • ROYGBIV • Ultraviolet (UV) • near = 2 x 10−7 < l < 4 x 10−7 m • far = 1 x 10−8 < l < 2 x 10−7 m • X-rays = 10−10 < l < 10−8m • Gamma rays = l < 10−10 Tro: Chemistry: A Molecular Approach, 2/e

10. Light and the Electromagnetic Spectrum

11. Chapter 7: Examples – EMR A stop light has a red (700 nm), yellow (580 nm) and green (530 nm) lights. Which has the highest frequency?

14. 2-Slit Interference Tro: Chemistry: A Molecular Approach, 2/e

15. Max Karl Ernst Ludwig Planck

16. Blackbody Radiation

17. Quantization of energy • Energies in atoms are quantized, not continuous. • Quantized means only certain energies allowed.

18. Chapter 7: Examples – EMR Calculate the energy of one quantum of red light (700 nm).

20. Chapter 7: Examples – EMR A certain lamp produces 5.0 J/s of energy in the blue region of the spectrum. How many photons of blue (470 nm) light would it generate if it were left on for 8.5 s?

21. Chapter 7: Examples – EMR If a light with a wavelength of 200 nm shines on sodium atoms with an ionization energy of 496 kJ/mol, what will be the speed of the electrons emitted?

22. Experiment 1 • Add an elemental gas to a cathode ray tube and get ----- colors • Hydrogen (H2) purple blue • Neon (Ne) red orange • Helium (He) yellow pink • Argon (Ar) lavender • Xenon (Xe) blue

23. Experiment 2 • Shine white light through a prism -- rainbow • A prism separates light of different wavelength, each color represents a different wavelength. Sundog – caused by ice acting as a prism.

24. Experiment 3 • Shine the colored light from our gas discharge tubes through a prism  get distinct bands of color (light).

29. Examples of Spectra Tro: Chemistry: A Molecular Approach, 2/e

30. Emission vs. Absorption Spectra Spectra of Mercury Tro: Chemistry: A Molecular Approach, 2/e

31. Chapter 7: Examples – EMR Calculate the wavelength of a photon emitted by a hydrogen atom when an electron makes a transition between the third and second principle quantum level.

32. John Dalton p124

33. J. J. Thomson and Ernest Rutherford p126

36. Wolfgang Pauli and Neils Bohr

39. Quantized Energy

41. Chapter 7: Examples – Energy Quantization A stream of laser photons has a frequency of 7.57 x 1014 Hz. • What is it’s energy? • What level can it get to?

42. Chapter 7: Examples – de Broglie • What is the wavelength in nm associated with a 0.080 kg ball moving at 70.0 km/hr? • How fast must the ball travel to have a wavelength of 0.0500 nm?

43. Trajectory vs. Probability Tro: Chemistry: A Molecular Approach, 2/e

44. How are n, l, and ml related?

45. Quantum Numbers

47. Electron Spin Experiment Tro, Chemistry: A Molecular Approach

48. ·equal to +1/2 or 1/2 ·necessary because each orbital contains 2 electrons and each electron needs its own space. Spin quantum number (ms)

49. Chapter 7: Examples – Quantum Numbers If n = 4, l = 2, ml = +2, what type of orbital is the electron located?

50. Chapter 7: Examples – Quantum Numbers Give the possible combination of quantum numbers for a 3s1 orbital.