1. CHEMISTRY 161 Chapter 7 Quantum Theory and Electronic Structure of the Atom www.chem.hawaii.edu/Bil301/welcome.html

2. 1. Structure of an Atom subatomic particles electrons protons neutrons

3. 17p 18n 17e 35 17 Cl mass number atomic number 18 neutrons 2. What forces combine atoms to molecules? e-e- classical physics predicts that electron falls into nucleus 1. Why are atoms stable?

4. 2. Properties of Waves Intensity Distance.. direction of propagation wavelength [m] amplitude

5. Intensity Time.. direction of propagation Period [s] T Frequency [s -1 ] [1 Hz = 1 s -1 ] Hertz

6. Frequency and Wavelength wavelengthfrequencyspeed of radiation meter (m)Hz or s -1 m s -1

7. LONG WAVELENGTH, LOW FREQUENCY

8. SHORT WAVELENGTH, HIGH FREQUENCY

9. Which wave has the longest wavelength?

10. The number of waves passing a given point per second is: 2 = THE FREQUENCY 1 = THE SPEED 3 = THE WAVELENGTH

11. light can be described as a wave

12. James Maxwell POSTULATE visible light consist of electromagnetic waves speed of propagation (speed of light) c = 300,000 ms -1

13. light has two components 1.Electric field component 2.Magnetic field component

14. ELECTROMAGNETIC SPECTRUM INCREASING FREQUENCY

15. Which color has the higher frequency? 1 = orange 2 = blue  = c Wavelength  (nanometers) VISIBLE SPECTRUM

16. The wavelength of the yellow light from a lamp is 589 nm. What is the frequency of the radiation?

17. Max Planck POSTULATE h is Planck’s constant h = 6.626 x 10 -34 J s

18. LiNaK Different atoms emit distinct light

19. Planck’s Quantum Theory HEAT ANALYSE Heat hollow object

21. CLASSICAL any amount of energy can be emitted or absorbed NON-CLASSICAL energy can be emitted or absorbed only in discrete quantities (little packages) energy is not continuous QUANTUM smallest amount of energy which can be absorbed/ emitted

22. E initial E final ABSORPTION OF A PHOTON atoms and molecules absorb discrete photons (light quanta)

23. THE PHOTOELECTRIC EFFECT light electron metal shine light on a piece of metal and electrons are emitted electrons are emitted only if the frequency of the light is greater than a minimum value depending on the metal 3. Properties of Photons

24. THE PHOTOELECTRIC EFFECT

25. Albert Einstein Electromagnetic radiation can be viewed as a stream of particle-like units called photons POSTULATE

26. de Broglie Duality of Wave and Corpuscle light has properties of a wave and of a particle

27. SUMMARY 1. light can be described as a waves of a wavelength and frequency 2. light can be emitted or absorbed only in discrete quantities (quantum – package - photon) 3. duality of wave and corpuscle

28. Homework Chapter 7, pages 245-252 problems