1 / 37

Chapter 5: Electrons In Atoms

Chapter 5: Electrons In Atoms. Wave Nature of Light. Electromagnetic Radiation – form of energy that exhibits wavelike behaviors as it travels through space Ex: visible light, microwaves, x-rays, radio, etc. Wavelength. Symbol – λ ( lambda )

cortez
Download Presentation

Chapter 5: Electrons In Atoms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 5: Electrons In Atoms

  2. Wave Nature of Light • Electromagnetic Radiation – form of energy that exhibits wavelike behaviors as it travels through space • Ex: visible light, microwaves, x-rays, radio, etc.

  3. Wavelength • Symbol – λ (lambda) • Defn – distance between equivalent points on a curve λ λ λ

  4. Frequency • Symbol – f • Defn – number of waves that pass a given point in a second • Unit: Hertz (Hz) • Ex: 300 Hz = 300 1/s = 300 s-1 = 1/s = s-1

  5. Amplitude • Defn – wave’s height from origin to crest crest amplitude origin

  6. Electromagnetic Waves • All EM waves travels at the speed of light (c) • c = 3 x 108 m/s • c = (wavelength)(frequency) c = λf = 3 x 108 m/s

  7. Wavelength and Frequency Relationship • Inversely related: as one increases, other decreases shortλ high frequency longλ low frequency

  8. Electromagnetic Spectrum • Defn – shows all forms of electromagnetic radiation

  9. Ex problem #1 • What is the wavelength of a microwave with a frequency of 3.44 x 109 s-1? c = λf c 3 x108 m/s 8.72 x 10-2 m = λ = = 3.44 x 109 s-1 f

  10. Ex problem #2 • What is the frequency of green light, which has a wavelength of 4.90 x 10-7 m? c = λf c 3 x108 m/s = = f = 4.90 x 10-7 m λ 6.12 x 1014 Hz

  11. Particle Nature of Light • Quantum – minimum amount of energy that can be gained or lost by an atom • Photoelectric Effect – emission of electrons from metal’s surface when light of specific frequency shines on surface light e- METAL

  12. Photon – particle of light • Photon Energy • Unit: joules (J) • formula Ephoton = hf h = Planck’s constant = 6.626 x 10-34 J·s f = frequency (s-1)

  13. Ex problem • What is the energy of a photon from the violet portion of the rainbow if it has a frequency of 7.23 x 1014 s-1? E = hf = (6.626 x 10-34 J·s) (7.23 x 1014 s-1) = 4.79 x 10-19 J

  14. Bohr Model of an Atom • Ground State – lowest energy state of an atom • Excited State – state when atom gains energy **pay attention to the electrons** • Bohr Model – shows electron orbit and energy level of an electron

  15. Bohr Model E1 = lowest energy level E3 > E2 > E1 E1 E2 E3

  16. in ground state, no energy radiated in excited state, electrons jump to higher energy level electron go from high E level to low E level photon emitted Ground State to Excited State 4 6 1) 5 4 2) 3 3 2 Energy of atom 2 3) 1 4) 1

  17. Atomic Orbitals • Defn – 3D region around nucleus describing specific electron’s location

  18. Principle Quantum Number (n) • Defn – indicates the energy level an electron is on - use periodic table to tell (look at rows) n = 1,2,3,…..

  19. Principal Quantum Number

  20. Energy Sublevels/Orbitals • Defn – shape of orbital that tells the path of the electrons • 4 sublevels: s, p, d, f Let’s focus on the s and p orbitals

  21. s orbital • Shape: electrons travel in a sphere

  22. s orbital 3s 1s 2s The greater the energy level, the bigger the orbital

  23. p orbital • Shape: dumbbell or figure 8 shaped

  24. Electron Configuration • Defn – arrangement of electrons in an atom Where are certain electrons located?

  25. Rules Governing Electron Configurations 1) Aufbau Principle – electrons occupy lowest energy orbital available - fill up level 1 first, then level 2, etc. 2) Pauli Exclusion Principle – there is a max number of electrons that occupy a single orbital (2)

  26. Rules Governing Electron Configurations 3) Hund’s Rule – if orbitals have equal energy, one e- will go in each orbital before doubling up 1 2 3 5 6 4

  27. Blocks On Periodic Table s s p d f

  28. Divisions of Orbitals • s orbital – 1 sublevel (2 e- max) • p orbital – 3 sublevels (6 e- max) • d orbital – 5 sublevels (10 e- max) • f orbital – 7 sublevels (14 e- max)

  29. Orbital Diagram • Nitrogen • How many electrons? • What energy level is nitrogen on? 7 n = 2 1s 2s 2p

  30. Orbital Diagram • Silicon • How many electrons? • What energy level is silicon on? 14 n = 3 1s 2s 2p 3s 3p

  31. Orbital Diagram • Copper • How many electrons? • What energy level is copper on? 29 n = 4 1s 2s 2p 3s 3p 4s 3d

  32. Electron Configuration Notation 2 2 4 • Oxygen (8 e-) • Sulfur (16 e-) • Vanadium (23 e-) • Zirconium (40 e-) 2s 2p 1s 2 2 6 2 4 2s 2p 3s 3p 1s 2 2 6 2 6 2 3 2s 2p 3s 3p 4s 3d 1s 2 2 6 2 6 2 10 6 2 2 2s 2p 3s 3p 4s 3d 4p 5s 4d 1s

  33. Noble Gas Notation • Rule: start from previous noble gas, then write the configuration • Oxygen • Sulfur • Vanadium • Zirconium 2 4 [He] 2s 2p 2 4 [Ne] 3s 3p 2 3 [Ar] 4s 3d 2 2 [Kr] 5s 4d

  34. Valence Electrons • defn – electrons in outer most energy level - located in highest s & p orbitals (max 8) N: Mg: Se: 2 2 3 5 valence e- 1s 2s 2p 2 2 6 2 2 valence e- 1s 2s 2p 3s 2 2 6 2 6 2 10 4 1s 2s 2p 3s 3p 4s 3d 4p 6 valence e-

  35. Electron Dot Structure • Defn – shows number of valence e- by diagram • Nitrogen (5 v.e.) • Magnesium (2 v.e.) • Selenium (6 v.e.) N Mg Se

More Related