1. Unit 7: Electrons 1

2. Electromagnetic (EM) radiation O A form of energy produced by electrical and magnetic vibrations, or by the movement of electrically charged particles O Can travel in a “vacuum” (they do NOT need a medium) O Travel at the speed of light 2

3. Electromagnetic Spectrum O Page 120 Frequency and energy have a direct relationship. Watch this.Watch this 3

4. The Electromagnetic Spectrum Shows all types of EM radiation Red Martians Invaded Venus Using X-Ray Guns Shorter wavelength, high frequency light has higher energy. Write this on your diagram –Radio wave has the lowest energy. –Gamma ray has the highest energy. High energy electromagnetic radiation damages biological molecules. It is called ionizing radiation

5. Visible light O Has wave-like and particle-like properties O A particle of light is called a photon. Make the colors of the rainbow ROY. G. BIV Each color has a different wavelength, energy, and frequency 5

6. Wave properties O (f) Frequency-number of waves that pass a given point per unit of time. (Hz) O ( ) Wavelength- distance between similar points in a set of waves (crest to crest.) (m) 6

7. Wave properties O Amplitude- distance from crest or trough to the normal (baseline). Energy- Waves transmit energy. The amount of energy determines the amplitude and the frequency. 7

8. Energy & Amplitude O DIRECTLY related O Determines the intensity of light O The bulb on the right is emitting energy with a higher amplitude than the bulb on the left 8

9. Amplitude and Wavelength 9 Write this

10. Speed of the wave O 10 Write everything

11. Practice Problem O What is the wavelength of a radio wave with a frequency of 1.01 x 10 8 Hz? c = λ X f 3.00 X 10 8 = λ X 1.01 x 10 8 λ = 3.00 X 10 8 1.01 x 10 8 λ = 2.97 m 11

12. Energy of Electromagnetic Waves O The energy is carried in small packages called photons. The energy carried in each photon is calculated by: E = hf O E = energy O h = Planck’s constant =h = 6.63 x 10 -34 Js O energy and frequency are DIRECTLY related 12 Write everything

13. Electrons and Light Vocabulary: Ground State- the electron occupies the LOWEST energy level. Excited State- the electron temporarily occupies a HIGHER energy level. Energy is needed to go up a level Photons are released when falling down a level. 13 Write everything

14. Quantum O The specific amount of energy absorbed to excite an electron O The specific amount of energy released when an electron falls to the ground state. Energy inEnergy out 14

15. Atoms and Photons and Color O Each atom’s electrons “jump” to certain excited states. O Each “fall” releases a photon of a certain wavelength. These wavelengths of light correspond to certain colors of light. The colors of light emitted by an atom’s electrons can be used to identify the element. O The brightness of the color depends on the number of photons emitted. 15

16. Where are the Electrons in the Cloud? O Electrons are located at specific distances from the nucleus O The distance from the nucleus determines the amount of energy associated with the electrons 16

17. Principal Energy Levels O 7 Energy Levels O Abbreviated “n” O n= 1 is closest to nucleus and has least energy O n=7 is furthest from nucleus and has most energy 17

18. Energy Levels O Electrons are restricted to an energy level. O Electrons occupy the lowest energy level possible because electrons are lazy! O On the periodic table, each period (horizontal row) is an energy level

19. Energy levels contain sublevels O There are four types of sublevels O s, O p, O d, O f

20. Sublevels have different energies spdf: sublevel energies in increasing order s is lowest energy p is next highest d follows p in energy f is highest 20

21. Energy Sublevels & the PT Label your periodic tables according to the diagram

22. Orbital =The answer to a math problem. O The math question? O Solve the above equation to tell us where the electron is found in the atom. O The answer tells you what level and sublevel the electron can probably be found.

23. Each sublevel has orbitals that contain electrons One orbital can contain 2 electrons. They must have opposite spin. Pauli Exclusion Principle 23

24. O The maximum number of electrons that can occupy a specific energy level can be calculated O Formula is 2n 2 n = energy level O Calculate electrons for the 3rd energy level: O 2(3) 2 = 18 electrons in the 3rd level 24

25. Locating Electrons O There are two ways to show where the electrons are found in the atom O Orbital filling diagrams O Electron configurations 25

26. Follow the rules when placing electrons O Aufbau Principle- electrons go to the lowest energy level first. 26

27. Follow the rules when placing electrons O Hunds Rule- no orbital shares electrons until it has to share. Space them out to minimize repulsion of electrons. 27

28. Locating Electrons

29. Orbital Filling Diagrams O Use arrows to represent electrons in orbitals. O The number of arrows must match the number of electrons contained in the atom 29

30. Practice O Hydrogen: O Oxygen: O Argon: O Copper: 1s 1 1s 1 2s 2 2p 4 1s 2 2s 2 2p 6 3s 2 3p 6 30

31. Electron Configuration O Shorthand method for describing the arrangement of electrons O Composed of the principal energy level followed by the energy sublevel and includes a superscript with the # of electrons in the orbitals of that sublevel

32. Electron Configuration O Electron Configuration is ordered the way you read a book: from left to right and top to bottom O Note that d orbital is 1 energy level behind and the f orbital is 2 energy levels behind the s & p orbitals The order: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6 etc.

33. Electron Configuration IAVIII A 1s IIAIII A IV A VAVI A VII A s 2sspppppp 3sspppppp 4ssddddddddddpppppp 5ssddddddddddpppppp 6ssfdddddddddpppppp 7ssfdd fffffffffffffd fffffffffffffd 33

34. Orbital Filling Diagrams 34

35. Electron Configuration O Electron Configuration: 1s 2 2s 2 2p 6 O Orbital Filling Diagram: O Orbital image:

36. Noble Gas Configuration O Shorthand electron configuration 1. Give the symbol of the noble gas in the previous energy level in brackets 2. Give the configuration for the remaining energy level Example: Sulfur = 1s 2 2s 2 2p 6 3s 2 3p 4 [Ne]3s 2 3p 4

37. Valence Electrons O Valence electrons: found in the outermost energy level O These electrons are used for bonding O Example: Nitrogen = 1s 2 2s 2 2p 3 O Add up the number of e- (superscripts) in the highest energy level O Nitrogen has 2 + 3 = 5 valence electrons O Core electrons: found in the inner O energy levels. Nitrogen = 1s 2 2s 2 2p 3

38. The number of valence electrons is equal to the number in the 1’s place of the group number 38

39. Lewis-Dot Diagrams O Lewis Dot Diagrams are a way to represent the valence electrons in an atom. O Element’s symbol represents the nucleus and inner-level electrons O Dots represent the valence electrons O Dots are placed one at a time on the four sides of the symbol, then paired until all valence electrons are used… O Maximum of 8 e- will be around the symbol 39

40. Lewis-Dot Diagrams 40

41. Ions O Ions are atoms that have gained or lost electrons; indicated by a superscript that shows the ion’s charge O Cl 1s 2 2s 2 2p 6 3s 2 3p 5 O Cl -1 1s 2 2s 2 2p 6 3s 2 3p 6 chlorine added an electron

42. Chlorine adds a valence electron and becomes a negative ion (anion). O Sodium loses a valence electron and becomes a pawsitive ion (cation).

43. Can you tell which atoms are in ground state and which are excited ? 1s 2 2s 2 2p 6 3s 2 4p 1 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 1s 2 2s 2 2p 3 4s 1 1s 2 2s 2 2p 6 3s 2 3p 6 3d 8 43