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3.2 Lecture 2008

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3.2 Lecture 2008

  1. 1. 3.2 A Guided Tour of the Periodic Table Pages 77 - 85
  2. 2. Goal 1 Explain the relationship between the periodic table and the arrangement of electrons within an atom.
  3. 3. <ul><li>Order based on number of protons </li></ul><ul><li>Similar elements grouped together </li></ul><ul><li>Similarities then occur in regular pattern </li></ul><ul><li>Helps predict properties </li></ul>
  4. 4. <ul><li>Horizontal rows are called “periods” </li></ul><ul><li>Can be used to determine electron arrangement </li></ul><ul><li>Works up to element 20, Ca </li></ul>
  5. 5. <ul><li>Each horizontal row is an energy level </li></ul><ul><li>Each square counts as an electron in that energy level </li></ul>
  6. 7. <ul><li>Li has 3 electrons  level 1 = 2e - level 2 = 1 e - </li></ul>
  7. 8. <ul><li>N has 7 electrons  Level 1 = __ Level 2 = __ </li></ul>
  8. 9. <ul><li>Each vertical column is a Group </li></ul><ul><li>Elements in a group have similar chemical properties </li></ul><ul><li>Valence electrons 1, 2, 13-18 </li></ul>
  9. 11. Goal 2 Explain ion formation
  10. 12. <ul><li>Purpose of Ionization </li></ul><ul><ul><li>Full outermost shell </li></ul></ul><ul><ul><li>Gain or lose valence electrons </li></ul></ul><ul><ul><li>Results in imbalanced electronic charge </li></ul></ul>
  11. 13. <ul><li>Loss of electron yields “+” charge </li></ul><ul><ul><li>Lose 1 electron  1+ charge </li></ul></ul><ul><ul><li>Lose 2 electrons  2+ charge </li></ul></ul><ul><ul><li>Lose 3 electrons  3+ charge </li></ul></ul><ul><li>Happens with small # of valence electrons </li></ul><ul><li>Left-side of the periodic table </li></ul><ul><ul><li>Which groups??? </li></ul></ul>
  12. 14. <ul><li>What will the charge be on the following ions? </li></ul><ul><ul><li>H </li></ul></ul><ul><ul><li>Li </li></ul></ul><ul><ul><li>Ca </li></ul></ul><ul><ul><li>K </li></ul></ul><ul><ul><li>W </li></ul></ul>
  13. 15. <ul><li>Gain of electrons yields “-” charge </li></ul><ul><ul><li>Gain 1 electron  1- charge </li></ul></ul><ul><ul><li>Gain 2 electrons  2- charge </li></ul></ul><ul><ul><li>Gain 3 electrons  3- charge </li></ul></ul><ul><li>Happens with high # of valence electrons </li></ul><ul><li>Which groups??? </li></ul>
  14. 16. <ul><li>What will the charge be on the following ions? </li></ul><ul><ul><li>F </li></ul></ul><ul><ul><li>Cl </li></ul></ul><ul><ul><li>S </li></ul></ul><ul><ul><li>P </li></ul></ul><ul><ul><li>N </li></ul></ul>
  15. 17. Goal 3 Use the periodic table to determine the number of protons, electrons, and neutrons
  16. 18. <ul><li>Atomic number </li></ul><ul><ul><li>Protons </li></ul></ul><ul><ul><li>Electrons </li></ul></ul>6 2 4 carbon 12 C
  17. 19. <ul><li>Mass number </li></ul><ul><ul><li>Protons + neutrons </li></ul></ul>6 2 4 carbon 12 C
  18. 20. <ul><li>Protons = atomic number </li></ul><ul><li>Electrons = atomic number </li></ul><ul><li>Neutrons = mass number – atomic number </li></ul>
  19. 21. Goal 4 Work with isotopes and average atomic mass
  20. 22. <ul><li>Isotopes </li></ul><ul><ul><li>Same number of protons </li></ul></ul><ul><ul><li>Different number of neutrons </li></ul></ul><ul><ul><li>Chemical properties remain same </li></ul></ul><ul><ul><li>Mass number changes </li></ul></ul><ul><ul><li>Mass changes </li></ul></ul>
  21. 23. <ul><li>Example </li></ul><ul><ul><li>One atom of “Carbon” </li></ul></ul><ul><ul><ul><li>6 protons </li></ul></ul></ul><ul><ul><ul><li>6 neutrons </li></ul></ul></ul><ul><ul><ul><li>Atomic mass ~ 12 </li></ul></ul></ul><ul><ul><li>One isotope atom of “Carbon – 14” </li></ul></ul><ul><ul><ul><li>6 protons </li></ul></ul></ul><ul><ul><ul><li>8 neutrons !!! </li></ul></ul></ul><ul><ul><ul><li>Atomic mass ~ 14 </li></ul></ul></ul>
  22. 24. <ul><li>How many neutrons are in the following isotopes? </li></ul><ul><ul><li>Nitrogen -15 </li></ul></ul><ul><ul><li>Sulfur – 35 </li></ul></ul><ul><ul><li>Calcium – 45 </li></ul></ul><ul><ul><li>Iodine - 131 </li></ul></ul>
  23. 25. <ul><li>The mass of atoms and isotopes </li></ul><ul><li>Atomic mass unit </li></ul><ul><ul><li>1.0 amu = one proton = one neutron </li></ul></ul>
  24. 26. <ul><li>Average atomic mass </li></ul><ul><ul><li>Weighted average of isotopes </li></ul></ul><ul><ul><li>Nearest whole number indicates most common isotope </li></ul></ul>6 2 4 carbon 12.011 C

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