Quanta, Light, and Electron Configurations

1. Quanta, Light, and Electron Configurations

2. Objectives I can explain the key properties of electromagnetic radiation I can explain how quantum theory relates to electromagnetic radiation I can explain the key characteristics of Bohr’s Atom

3. Review from yesterday Are marker colors compounds or mixtures? How could you determine which one it is?

4. Warm Up: Solve the first three problems on the Isotope worksheet The remaining questions are for extra practice, if you need it

5. What is light? What is considered light and what is not considered to be light? What makes up light? Does light influence color? How can we determine what light is made of?

6. Light Investigation: -Using the spectroscope Record the following observations: -What is light made of? -How does light change? -What effects the spectrum of color? -What is the spectroscope actually showing you?

7. Results of Investigation? -What is light made of? -How does light change? -What effects the spectrum of color? -What is the spectroscope actually showing you?

8. What is light? Light is Electromagnetic Radiation that make things visible

9. Electromagnetic Radiation: -Any form of radiant energy that is a part of the electromagnetic spectrum -Examples of radiant energy: UV light, visible light, X-rays, gamma rays, microwaves ******Produced when an atom absorbs energy

11. Electromagnetic Spectrum -Different ranges of radiant energy -All forms are shown on this spectrum

12. How does this relate to the color of an object? -Absorbed -Refracted https://ed.ted.com/lessons/how-do-we-see-color-colm-kelleher

13. Electromagnetic Spectrum: Wave like Properties Wavelength: distance from crest to crest Frequency: number Of crests that a pass a reference pt every sec

14. Diffraction -Wave property of electromagnetic radiation -Bending of electromagnetic radiation as it passes around the edge of an object/narrow opening

15. Trends in the Electromagnetic Spectrum -Relationship between wavelength and frequency -Relationship between energy and wavelength -Relationship between energy and frequency -What color has the most energy,How do you know?

16. Next Great Discovery- 1800 -Wollaston -Studied light using a prism -Determined that the spectrum of sunlight is not continuous

17. Fraunhofer Lines -Dark lines in the light spectrum

18. What causes these lines???

19. 1860- Bunsen -Studied the light given off by elements vaporized in a flame using…… -Discovered: Atomic emission Spectra

20. Atomic Emission Spectra -Bright line spectra -Bright colored lines that are in the exact same wavelength as the dark Fraunhofer lines

21. Conclusions: Atomic Emission Spectrum *******Each element emits a specific electromagnetic radiation when its atoms are heated to the correct temperature

22. Atomic Absorption Spectrum -Elements also absorb electromagnetic radiation when illuminated -Dark-line spectrum -These correspond to the same wavelengths on the emission spectrum

23. Example:

25. Back to the original problem: -What explains the dark, Fraunhofer lines of the sun?

26. Review Question: What is electromagnetic radiation? Which is emission and which is absorption?

27. What causes the atomic spectra?

28. How the atomic spectrum relates to our favorite subatomic particle *Spectra: plural of spectrum -Interactions of electromagnetic radiation and electrons -Electrons gain energy, lose energy, emitting colors -As move forward we will learn more about this, but keep it in mind

30. Insert break and use demonstration then finish lecture…..

31. Wait, it’s only 1860….. -Problems with the theory that electromagnetic radiation behaves like a wave…...

32. Limits to the idea the electromagnetic radiation ONLY has particles of a wave -Burning a metal rod

33. According to the Wave Behavior -Intensity of light should be the largest factor influencing the electrons -BUT, it has nothing to do with it

34. How do we know? -Einstein -The electromagnetic radiation has to be at a certain frequency to effect the metal -Requires a threshold frequency -Intensity has nothing to do with it

35. Plank Saves the Day -Quantum Theory -What if, electromagnetic radiation behaves like a wave and a particle

36. Quantum Theory Quantum: Smallest discrete quantity of a form of energy Quantum Theory: A model that shows that energy is emitted in discrete quantities called quanta

37. Quantized: -Values that are restricted to whole number multiples of a base value What does this mean? An object is made of a discrete number of particles, so it can only emit a certain amount of quanta

38. Step Ladder Analogy Up: Absorb Down: Released

39. How does this relate back to light? -Photon -Quantum of electromagnetic radiation

40. What does a photon look like?

42. Where are we in history at this point?

43. 1911,Rutherford’s model was the model of the atom Properties of his atomic model: -Atom mostly empty space But a problem he had with his model What prevents the Electrons from falling into the nucleus?

44. So what does Bohr have to do with this?

45. What did Bohr’s Model Look like? -Discrete energy levels, n, where electrons reside -Circle the nucleus -Electron cannot gain or lose energy inside the orbit, Only can move up or down -lowest energy orbit is closest to the nucleus

46. Key concepts associated with this model: Quantum number: n, number that specifies energy and location of an electron (1,2, 3…) Electron Transition: Movement of electrons between energy levels Ground State: n=1, lowest energy level, closest to the nucleus

47. Excited State -When an electron is at a higher Energy level than the ground state