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The Electron Structure of the Atom

The Electron Structure of the Atom. The Quantum Model. The quantum model emphasizes the wave nature of electrons. Quantum Numbers. Quantum numbers are solutions to the wave equations of electrons. Scientists use a set of 4 quantum numbers to determine an electron’s location around an atom.

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The Electron Structure of the Atom

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  1. The Electron Structure of the Atom

  2. The Quantum Model The quantum model emphasizes the wave nature of electrons.

  3. Quantum Numbers • Quantum numbers are solutions to the wave equations of electrons. • Scientists use a set of 4 quantum numbers to determine an electron’s location around an atom.

  4. Where are the Electrons? • Electrons exist in principal energy levels that correspond to Bohr’s orbits: 1, 2, 3, 4, 5, … • Principal energy levels are divided into 4 types of sublevels: s, p, d, and f.

  5. Where are the Electrons? • The sublevels contain orbitals. • Each orbital can hold up to two electrons.

  6. Principal Quantum Number (n) • Identifies the principal energy level • Correlates to Bohr’s orbits • n = 1, 2, 3, 4, 5, 6, or 7 for the ground state e−. • The total number of e− in a level is 2n2.

  7. Azimuthal Quantum Number (l) • Identifies the sublevel • Different sublevels have different shapes. • 4 types of sublevels: s, p, d, f

  8. The Quantum Model s, p, d, f. and Principal energy levels are divided into four types of sublevels: s p d f S Silly, people p don’t d fly. f

  9. The Quantum Model • The sublevels contain orbitals. • The orbitals contain the electrons. • Each orbital can hold up to two electrons.

  10. The Quantum Model • A number is associated with each type of sublevel. s = 0 p = 1 d = 2 f = 3

  11. The Quantum Model Do all levels have all four sublevels? No. Which levels have which sublevels?

  12. The Quantum Model Levels & Sublevels 1st ……… s 2nd ……… s, p 3rd ……… s, p, d 4th ……… s, p, d, f 5th ……… s, p, d, f 6th ……… s, p, d 7th ……… s, p

  13. Magnetic Quantum Number (m) • Identifies the orbital • Describes how the e− responds to magnetic fields • Each sublevel has 2l + 1 orbitals.

  14. Electron-Spin Quantum Number (ms) • Identifies the spin • Each orbital can hold only 2 e−. • Each e− in an orbital has an opposite reaction to a magnetic field.

  15. Electron-Spin Quantum Number (ms) • Scientists call this property “spin.” • The values for the electron-spin quantum numbers are +½ or −½.

  16. Pauli Exclusion Principle Electrons can occupy the same orbital only if they have opposite spins.

  17. Pauli Exclusion Principle • Said to be “spin-paired” • Represented by the direction of an arrow

  18. Pauli Exclusion Principle Because of this principle, the MAXIMUM number of electrons that can occupy any orbital is 2. MAXIMUM 2

  19. Sublevels & Orbitals The “s” Sublevel It has only 1 orbital. So, it can hold only 2 electrons.

  20. Sublevels & Orbitals The “p” Sublevel It has 3 orbitals. + + = So, it can hold 6 electrons.

  21. Sublevels & Orbitals The “d” Sublevel It has 5 orbitals. So, it can hold 10 electrons.

  22. Sublevels & Orbitals The “f” Sublevel It has 7 orbitals. So, it can hold 14 electrons.

  23. Sublevel # orbitals # e− s 1 2 p 3 6 d 5 10 f 7 14

  24. The Sublevels • Remember that their shapes are only mathematical representations of electron behavior. • They help visualize the electrons and account for their properties.

  25. Question What are the four sublevels named? • a, b, c, d • w, x, y, z • s, p, d, f • e, f, g, h

  26. The Quantum Model Levels & Sublevels Do all levels have all four sublevels? No. Which levels have which sublevels?

  27. The Quantum Model Levels & Sublevels 1st ……… s 2nd ……… s, p 3rd ……… s, p, d 4th ……… s, p, d, f 5th ……… s, p, d, f 6th ……… s, p, d 7th ……… s, p

  28. Energies of Sublevels In what order do the sublevels fill? 1s, 2s, 3s, 4s, 5s, … ? 1s, 2s, 2p, 3s, 3p, 3d, 4s, … ? Some other order?

  29. Order of Filling • Electrons fill the sublevels in order of increasing energy. • Whichever sublevel is lowest in energy receives electrons first, then the next lowest sublevel, and so on.

  30. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p

  31. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p

  32. Question Which sublevel fills after 3p? • 4s • 3d • 4p • 3s • 2p

  33. Question Which sublevel fills after 6s? • 6p • 7s • 4f • 5s • 5p

  34. Question Which sublevel fills after 7p? • 7s • 6p • 6d • 3f • There is no next sublevel.

  35. Periodic Table & Electron Configuration • Atomic numbers increase from left to right. • Each row corresponds to the next principal energy level. • Certain regions correspond to sublevels.

  36. The Aufbau Principle:How to Build an Atom The arrangement of electrons in an atom may be determined by the addition of electrons to a smaller atom.

  37. The Aufbau Principle:How to Build an Atom In the progression from hydrogen up to larger elements, each successive element has one additional electron and one additional proton.

  38. Electron Configuration • It is a shortcut to show the location of an electron in an atom. • Write 1s followed by a superscript 1 or 2 to denote how many electrons are in the 1s sublevel.

  39. E− Configuration of Elements H1s1 He1s2 Li1s2 2s1 Be1s2 2s2 B1s2 2s2 2p1 C1s2 2s2 2p2 N1s2 2s2 2p3 O1s2 2s2 2p4 F1s2 2s2 2p5 Ne1s2 2s2 2p6

  40. Question Which sublevel holds the first electron? • 1s • 2s • 2p

  41. Question Which sublevel holds the second electron? • 1s • 2s • 2p

  42. Question Which sublevel holds the third electron? • 1s • 2s • 2p

  43. Question Which sublevel holds the fourth electron? • 1s • 2s • 2p

  44. Question Which sublevel holds the fifth electron? • 1s • 2s • 2p

  45. Question What comes after 2p6 in electron configuration? • 2p7 • 3s1 • 3p1 • 2d1 • No more e− can be added.

  46. Orbital Notation Another method of showing the location of an electron in an atom • Write 1s, 3p, etc. for each level and sublevel containing electrons. • Use lines to represent orbitals. • Use arrows to show the e− in the orbitals.

  47. H 1s 1s 1s 2s 1s 2s He Li Be Orbital Notation

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