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Modern Atomic Model

Modern Atomic Model. Periodic Law. When elements are arranged in order of increasing atomic number, the elements with similar properties occur at periodic (regular) intervals. The periodic table is a graphical representation of the periodic law. Periodic Table.

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Modern Atomic Model

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  1. Modern Atomic Model

  2. Periodic Law • When elements are arranged in order of increasing atomic number, the elements with similar properties occur at periodic (regular) intervals. • The periodic table is a graphical representation of the periodic law.

  3. Periodic Table Periods are the rows across – look at your gold periodic table – there are 7 periods Groups or Families are the columns – look at your gold periodic table – there are 2 sets of numbers above the columns – some regular and some Roman numerals. We will use the regular numbers so there are Groups 1 – 18.

  4. Electron orbits • Neils Bohr had electrons in energy levels. His planetary model had electrons in orbits.

  5. Electron orbits • Orbits are predictable paths. • Great for planets but it doesn’t work for electrons.

  6. Electron orbits • Can’t know with any certainty where an electron is or where it will be an instant later. • Can’t plot the path of an electron. • Electrons are not in orbits!

  7. We need a new model!Atomic Orbitals • The modern quantum mechanical model has electrons in energy levels that have sublevels with orbitals. orbital - region around nucleus where an electron of particular energy is likely to be. Orbital for a hydrogen atom Think of the places where you would find a firefly in the dark.

  8. It’s not really that hard. • Get out your laminated gold periodic table. • Refer to it as we go through a whole bunch of mind-boggling slides!!!!!

  9. We are going to look at the atomic numberson the table as electron numbers—each electron added to an atom occupies a space on the table.

  10. s-block p-block d-block f-block

  11. Let’s look at the periodic table as a “block diagram” Each block is a sublevel within an energy level s p d f

  12. Sublevels have orbitals • Each orbital can hold a maximum of 2 electrons

  13. s-block p-block d-block f-block

  14. Go across any row in an s sublevel– how many numbers (electrons) across? At 2 electrons/orbital how many orbitals in an s sublevel?

  15. Go across any row in a p sublevel– how many numbers (electrons) across? At 2 electrons/orbitalhow many orbitals in a p sublevel?

  16. Go across any row in a d sublevel– how many numbers (electrons) across? At 2 electrons/orbitalhow many orbitals in a d sublevel?

  17. Go across any row in an f sublevel– how many numbers (electrons) across? At 2 electrons/orbitalhow many orbitals in an f sublevel?

  18. Energy Levels Have Sublevels s sublevel 1 orbital p sublevel 3 orbitals 5 orbitals d sublevel

  19. Number of Orbitals /Sublevel 1 for an s sublevel, 3 for a p sublevel, 5 for a d sublevel and 7 for an f sublevel. • The maximum number of electrons in an orbital does not vary. It is 2.

  20. Atomic Orbitals

  21. Arrangement of Sublevels in Energy Levels • Energy level 1 has 1 sublevel 1s • Energy level 2 has 2 sublevels 2s, 2p • Energy level 3 has 3 sublevels 3s, 3p, 3d • Energy level 4 has 4 sublevels 4s, 4p, 4d, 4f Number of sublevels = Energy Level

  22. s sublevel has 1 orbital s orbital: lowest energy holds 1 pair of electrons 1s 2s 3s 1s

  23. p sublevel has 3 orbitals p orbitals: hold 3 pairs of electrons p x

  24. d sublevel has 5 orbitals d orbitals: holds 5 pairs of electrons

  25. f sublevel has 7 orbitals f orbitals: hold 7 pairs of electrons Orbital Gallery

  26. 1st Energy Level s Electrons will fill in the sublevel with the lowest energy state first before filling in the next sublevel. s 2nd Energy Level p s Increasing Energy 3rd Energy Level p It so happens that the 4s sublevel is at a lower energy state than the 3d sublevel. d Increasing Distance from Nucleus s p 4th Energy Level d Electrons will fill in the 4s sublevel before they go back and fill the 3d sublevel. s f p 5th Energy Level d f

  27. s-block p-block d-block f-block

  28. 1s 1s 1 2 2s 2p 3 3p 3s 4 4p 4s 3d 5p 4d 5 5s 6 6s 5d 6p 7s 6d 7 4f 5f

  29. Block Diagram s p 1 2 3 4 5 6 7 d (n-1) 6 7 f (n-2) © 1998 by Harcourt Brace & Company

  30. Getting Started: • Each box represents an orbital • Orbitals are in groups according to sublevels • Arrows represent electrons • Any single orbital can hold a maximum of 2 electrons

  31. A. General Rules • Each orbital can hold TWO electrons with opposite spins.

  32. A. General Rules • Electrons fill the lowest energy orbitals first. • “Lazy Tenant Rule”

  33. A. General Rules • Within a sublevel, place one e- per orbital before pairing them. • “I don’t want to share my room if I don’t have to!” RIGHT WRONG

  34. Block Diagram s p 1 2 3 4 5 6 7 d (n-1) 6 7 f (n-2) © 1998 by Harcourt Brace & Company

  35. 2s 2p 1s B. Notation • Orbital Diagram O 8e-

  36. Homework Read pages 135 – 138 Do Orbital Diagrams Worksheet – both sides.

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