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Understanding Electron Addresses and Quantum Numbers in Chemistry

Learn about the rules governing electron location and movement, including the Heisenberg Uncertainty Principle. Understand quantum numbers and electron configurations through a comprehensive guide. Homework assignments included.

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Understanding Electron Addresses and Quantum Numbers in Chemistry

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  1. ELECTRONS AND THEIR LOCATION ELECTRON ADDRESSES

  2. RULES TO REMEMBER • HEISENBERG UNCERTAINTY PRINCIPLE –Cannot know the exact location of an electron. Fundamentally impossible to know both the location and momentum/velocity of an electron at the same time. • The quantum mechanical model merely suggests the probability of the electron location. • No circular orbits – Sorry Bohr!

  3. Aufbau Principle • Electrons fill the lowest possible energy level. • Energy levels correspond to period number on the Periodic Table. • How many energy levels are there?

  4. Pauli Exclusion Principle • No more than two (2) electrons in an orbital.

  5. Hund’s Rule(s) • 1) Orbitals of equal energy must fill singly before doubling. That means each must have one electron before any of that same level can have two electrons. • 2. All electrons in singly occupied orbitals have the same spin direction • 3. Pairs of electrons in the same orbital have opposite spin.

  6. QUANTUM NUMBERS • Describe the electron’s “address” • 1st Quantum is the principle quantum – describes the energy level. (1,2,3, etc.) • 2nd Quantum describes the shape of the orbitals. s,p,d,f • 3rd Quantum describes the orientation of the orbital • 4th Quantum describes the spin of the electron • we will use only the 1st & 2nd quantum numbers

  7. http://player.discoveryeducation.com/index.cfm?guidAssetId=163B32D5-42B7-402B-9AB6-C48679F58C9E&blnFromSearch=1&productcode=UShttp://player.discoveryeducation.com/index.cfm?guidAssetId=163B32D5-42B7-402B-9AB6-C48679F58C9E&blnFromSearch=1&productcode=US

  8. Shapes of orbitals • s on page 371 • p on page 372 • d on page 374

  9. What do you think the 5th energy level looks like? • The pattern stops – it looks like the 4th energy level • What about 6 & 7?

  10. Electron Configurations: Here we go now!! • Hydrogen is in the first period, therefore has only one energy level. The first energy level has only one orbital – the s orbital. Hydrogen has only 1 electron so, its electron configuration is • 1s1

  11. Helium is also in the first period, therefore has only one energy level. The first energy level has only one orbital – the s orbital. Helium has 2 electrons so, its electron configuration is • 1s2

  12. Lithium is in the second period, therefore has two energy levels. The first energy level has only one orbital – the s orbital. The second energy level has both s and p orbitals – one s and three p orbitals. Lithium has 3 electrons so, its electron configuration is • 1s22s1 Notice that the superscripts add up to the number of electrons.

  13. Let’s try beryllium • 2nd period with 4 electrons • 1s22s2 • Now boron - again, notice that the superscripts add up to the atomic number which is equal to the number of electrons • 1s22s22p1 • Carbon • 1s22s22p2

  14. Quick Quiz • A. How many electrons can the p orbitals hold if filled? • B. How many kinds of orbitals are in the 4th energy level? • C. What are the orbitals of the 2nd energy level? • D. How many f orbitals are there? • E. How many electrons can any one orbital hold? • F. At most, how many electrons in the 2nd energy level?

  15. That’s all for today!!

  16. Orbital Diagrams or Orbital Configurations • Use boxes and arrows to represent electrons in various energy levels. • Boxes must be labeled with regard to energy level and orbitals.

  17. H orbital configuration 1s

  18. H He orbital configuration 1s 1s

  19. H He Li orbital configuration 1s 1s 2s 1s

  20. H He Li Be orbital configuration 1s 1s 2s 1s 1s 2s

  21. B C orbital configuration 1s 2s 2p 1s 2s 2p

  22. N orbital configuration 1s 2s 2p

  23. Lewis Dot Structures • Element symbol represents atom nucleus and inner electrons. • Dots around the symbol represent valence (outermost energy level) electrons.

  24. Lewis dot structure 1 Symbol

  25. Lewis dot structure 1 2 Symbol

  26. Lewis dot structure 1 2 3 Symbol

  27. Lewis dot structure 1 2 3 Symbol 4

  28. Lewis dot structure 1 2 3 5 Symbol 4

  29. Lewis dot structure 1 2 5 3 Symbol 6 4

  30. Lewis dot structure 1 2 5 3 Symbol 6 4 7

  31. Lewis dot structure 1 2 3 5 Symbol 6 8 4 7

  32. Bohr Models • Use concentric circles to represent energy levels and the number of electrons in each.

  33. Bohr model H 1-

  34. Bohr model Li 2- 1-

  35. Bohr model Ne 2- 8-

  36. Bohr model S 2- 8- 6-

  37. Bohr model K 2- 1- 8- 8-

  38. Homework • Draw orbital diagrams for elements # 4,6,9,15, and 26 • Draw Lewis Dot structures for elements 1-20 • Draw Bohr models for elements # 2, 3, 5, 9, and 16

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