Unit 11 Modern Atomic Theory

1. Unit 11 Modern Atomic Theory The study of “What makes dematems act dat way?” Book Chapter 11

2. Objectives 1-3 • Well my friends, we have learned a lot of “What” in chemistry: What happens when these two chemical are reacted? What happens when energy is added to this chemical? • Well I think it is time, you are now mature enough to begin to understand “Why?”

3. Our journey begins by mapping out e-, the boogers that make reactions go! • so let us be with a little bit o’ history...

4. Classical mechanics developed by Isaac Newton(17th Century) successfully explained the motions of objects on earth and in space • they did a great job with the macroworld, but a lousy job of explaining how atoms and electrons moved • Einstein proved that Ike's Laws could not be applied to things traveling close to the speed of light so he made up his own ideas to explain this

5. 1 Describe what Niels Bohr said about the atom and its e-? e- are moving around the nucleus. The closer they are to the nucleus the less energy they have. The farther away, the more energy they have

6. Quantum mechanics or wave mechanics was developed in the 20's to explain how things move when they are traveling close to the speed of light like these e- boogers 2. What are the characteristics of light? • Light travels in waves so its has wavelength and frequency

7. 3. What is wavelength? • The distance between the wave peaks(for light, measured in nanometers 4. What is frequency? • Number of wave peaks that pass and given point over a period of time(measured in waves per second)

10. 5. Microwaves heating your food, radio waves transmitting music signals over space, light bulb transmitting heat and light, what do all these things have in common? • They all use a form of light to perform work for us 6. What is the sciency name for light? • Electromagnetic Spectrum

11. 7. Draw a line diagram describing the EM Spectrum

12. 8. What other characteristic does the EM spectrum have? • Light not only has wavelike characteristics but also particle like characteristic-this is called the dual nature of light 9. What is the number one particle characteristic of light? • The higher the frequency the more energy it will have

13. 10. What is the relationship between wavelength and frequency? • inverse

14. 11. So what is the difference between red light and blue light? • Blue light carries more energy than red light • Read Light as a Sex Attractant” and “Atmospheric Effects” on p 305 and p 307 respectively

15. A photon of red light (relatively long wavelength) carries less energy than a photon of blue light (relatively short wavelength) does.

16. Certain of the gases in the earth’s atmosphere reflect back some of the infrared (heat) radiation produced by the earth.

17. A composite satellite image of the earth's biomass constructed from the radiation given off by living matter over a multiyear period.

18. 12. So what does all this have to do with the atom? • Max Planck said that light was made up of particles traveling in waves, he was the first of the Particle Physicist

20. 13. What piece of the puzzle did the French scientist Louis De Broglie come up with? • DeBroglie suggested that if waves have a particle like character, maybe particles could also have wave like characteristics

21. Objective 4 • Be able to explain how atoms emit light

22. 14. Now all the pieces were together to try to explain the relationship between e- and light, what are these pieces? • e- travels as waves, each e- having its own frequency/wavelength depending on its energy • When e- gain absorb energy from the environment, their frequency goes up and they move farther away from the nucleus, this is called excited state

23. This is a very temporary situation, what goes up must come down • E- will lose the energy they gained and eventually fall back to their original spot-ground state • They do not always lose energy in one jump • Sometimes it may take several jumps

24. Each jump refers to light being given off, this light is called a photon • The smaller the jump the smaller the energy, the more to the red side of the spectrum will be seen • The bigger the jump the higher the energy, the higher the frequency, the more on the blue side will be seen

25. By understanding these jumps to be like going down stairs and not like going down a ramp, scientist began to understand that their was a pattern to the way e- existed and were able to explain why different elements gave off different light • E- could shed energy in jumps of one or more steps but always in step increments

26. The difference between continuous and quantized energy levels can be illustrated by comparing a flight of stairs with a ramp.

27. This is what is meant by saying that the energy levels around an atom are quantitized • So because atoms have different number of electrons and therefore different number of energy levels(stair steps) the combination of jumps that it can make are going to be different

28. The light that is emitted by all atoms are a combination of different lights corresponding to all the step combination that its electrons can make

29. An excited lithium atom emitting a photon of red light to drop to a lower energy state.

30. (a) A sample of H atoms receives energy from an external source). (b) The excited atoms (H) can release the excess energy by emitting photons.

31. When an excited H atom returns to a lower energy level, it emits a photon that contains the energy released by the atom.

33. Each photon emitted by an excited hydrogen atom corresponds to a particular energy change in the hydrogen atom.

34. (a) Continuous energy levels. Any energy value is allowed. (b) Discrete (quantized) energy levels. Only certain energy states are allowed.

35. The flames of metal salts are often brightly colored.

36. When salts containing Li+, Cu2+, and Na+ dissolved in methyl alcohol are set on fire, brilliant colors result.

37. When excited hydrogen atoms return to lower energy states, they emit photons of certain energies, and thus certain colors.

38. 15. What are the practical application for these concepts?

39. A neon sign celebrating Route 66

40. Objective 5 • Be able to explain why electrons position can never be completely explained

41. it was hoped that e- position could be mapped out for different atoms • Werner Heisenberg dashed this hope to the ground with his principle in 1927. 16 What is Heisenberg's Uncertainty Principle? • You can never know the exact location of an e- because once you think you’ve got it you have already added energy to it and it is no longer there-it has jumped to a higher energy level!

42. Well Hope was not all lost, perhaps we could not know the exact location of e- but maybe just maybe we could mathematically determine where the probably live 17. What was this mathematical model called? • Wave mechanical model 18. According to this model where to e- live? • Energy levels

43. Objective 6 • Be able to explain how electrons are arranged around the nucleus in energy levels, sublevels, and orbitals

44. these energy levels are assigned numbers, where 1 is closest to the nucleus 19. What does Quantum mechanics or Wave mechanics call the areas within the energy level where e- live? • Energy sublevels • number of sublevels in a energy level depend on the energy level number

45. 20. Describe the sublevel model: • sublevels are given letters to differentiate them: s, p, d, and f • the number of sublevels in an energy level is equal to the energy level number • Energy level 1 has 1 sublevel= s • Energy level 2 has 2 sublevels=s and p • Energy level 3 has 3 sublevels=s, p and d • Energy level 4 has 4 sublevels=s,p,d, and f • Energy levels 5,6, and 7 may have sublevels above f but we have no evidence to support it

46. 21. Draw a picture of the sublevel model 1s

47. 1s 2s

48. 1s 2s 2p

49. 1s 2s 2p 3s

50. N 1s 2s 2p 3s 3p