1 / 72

Periodic Properties

Periodic Properties. Chapter 7. Periodic Properties. Periodic Properties –depend on element’s position on table Ex: Groups H, Li, & Na all form similar oxides (H 2 O, Li 2 O, Na 2 O) Location gives you A LOT of information. Periodic Properties.

marcella
Télécharger la présentation

Periodic Properties

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. Periodic Properties Chapter 7

  2. Periodic Properties Periodic Properties –depend on element’s position on table Ex: Groups H, Li, & Na all form similar oxides (H2O, Li2O, Na2O) Location gives you A LOT of information

  3. Periodic Properties 2 Main Factors for Periodic Properties • Number of Levels – More levels, electrons held less tightly • More shielding • More electron to electron repulsion (PUSH) • Number of Protons – More protons hold electrons more tightly. Greater effective nuclear charge (Zeff) (PULL)

  4. Periodic Properties Properties we will study: • Size of Atoms • Size of Ions • Ionization Energy • Multiple Ionization Energy • Electron Affinity

  5. Size of Atoms Atomic Radius 1. Measured in picometers (1pm = 1 X 10-12 m) or Angstroms (1 Å = 100 pm) 2. Average radius ~100 pm (1 Å)

  6. Size of Atoms 3. Example: Bromine 1.14 Å 1.14 Å X 100 pm = 114 pm 1 Å

  7. Effective Nuclear Charge Zeff = Z-S Z = # protons S = # core electron

  8. What is the Zeff for chlorine (1s22s22p63s23p5)? Zeff = Z-S Zeff = 17- 10 = 7+

  9. Size of Atoms Down a group • Atoms get larger (more levels) • Shielding Effect – Core electrons shield the pull of the nucleus (more electron repulsion) (PUSH wins) H 1 level Zeff = 1+ Li 2 levels Zeff= 1+ Na 3 levels Zeff = 1+

  10. Size of Atoms

  11. Size of Atoms Across a period – atoms get smaller (same level), greater Zeff(PULL wins) Li F E config Levels Zeff

  12. Size of Atoms Si Cl

  13. Size of Ions A. Positive Ions 1. Example: Mg Mg+ E config Levels Zeff

  14. Size of Ions

  15. Size of Ions Positive ions always smaller • Fewer electrons to control • Less e- to e- repulsion

  16. Mg Mg+ Mg2+ E config Levels Zeff

  17. Size of Ions B. Negative Ions 1. Example: O O2- O3- E config Levels Zeff

  18. Size of Ions

  19. Size of Ions Negative ions always larger • More electrons to control • More e- to e- repulsion

  20. More levels If same Greater Zeff (same levels, greater Zeff smaller) If same Ions Positive = smaller(less electron repulsion) Negative = Larger (more electron repulsion)

  21. Size Review Which is larger and why? Li or K S or S2+ Mg or S O or Te

  22. Size Review Kurveball K or K+

  23. Ionization Energy A.Ionization energy – The energy needed to remove an electron from an isolated gaseous atom or ion Na  Na+ + e-

  24. He Ne Ar H Li Na K

  25. A high energy photon may ionize an atom (completely remove the electron) PHOTOELECTRIC EFFECT A low energy photon will excite an electron BOHR MODEL

  26. Ionization Energy B. Ionization energy is inversely proportional to atomic radius Examples: Li (520 kJ/mol) F (1681) Na (496 kJ/mol) Cl (1251)

  27. Ionization Energy Which has the higher Ionization Energy and why? C or O Na or Cl C or Sn Mg or Ra

  28. Multiple Ionization Energy Multiple Ionizations - Removing more than one electron 1st Mg  Mg+ + e- 738 kJ/mol 2nd Mg+  Mg2+ + e- 1450 kJ/mol 3rd Mg2+  Mg3+ + e- 7732 kJ/mol There is a large jump once you reach Noble Gas Configuration (Fewer levels, spike in Zeff)

  29. Multiple Ionization Energy

  30. Multiple Ionization Energy 1st Al  Al + + e- 577 kJ/mol 2nd Al +  Al 2+ + e- 1816 kJ/mol 3rd Al2+  Al3+ + e- 2744 kJ/mol 4th Al3+  Al4+ + e- 11580 kJ/mol

  31. Multiple Ionization Energy Examples: a. Where will the large jump in I.E. occur for: Be B P b. Element X has a large jump between its 4th and 5th I.E. To what group does it belong?

  32. Electron Affinity • Energy change that occurs when an electron is added to an isolated gaseous atom or ion • Ease with which an atom gains an electron • Cl(g) + e-  Cl-(g) DE = -349 kJ/mol • Positive for noble gases (don’t want electrons)

  33. Properties of Metals • Malleable and ductile • Good conductors • Large radius/Low ionization energy • Form positive ions (+2 and +3 for transition metals)

  34. Metal Oxides • Most metals oxidize easily in the atmosphere 2Ni(s) + O2(g)  2NiO(s) • Metal oxides are bases Metal Oxide + Water  Metal hydroxide (base) Na2O(s) + H2O(l)  2NaOH(aq) CaO(s) + H2O(l)  Ca(OH)2(aq) Metal Oxide + Acid  Salt + Water MgO(s) + HCl(aq)  MgCl2(aq) + H2O(l) NiO(s) + H2SO4(aq)  NiSO4(aq) + H2O(l)

  35. Al(s) + O2(g)  Zn(s) + O2(g)  CaO(s) + H2O(l)  Li2O(s) + H2O(l)  Al2O3(s) + HNO3(aq)  CuO(s) + H2SO4(aq) 

More Related