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AP Chemistry – Class 52

Ascorbic Acid

Ascorbic Acid

Dates

  • Period E  – Thursday, January 10th
  • Period F – Thursday, January 10th

Class Business

Big Idea: How do atoms arrange themselves in a compound?

Lewis Dot Structures

  • models – not “real”
  • valence electrons only
  • representative elements only
  • formal charge determination
  • multiple bonds

How To Construct Lewis Diagrams

  • Place the least electronegative atom in the central position (except hydrogen), surrounded by the remaining atoms
  • Calculate the total number of valence electrons available for the whole molecule or ion.
  • If the species under consideration is a polyatomic ion add or subtract as needed
  • Draw one line from the center atom to each of the outside atoms to symbolize a single bond.
  • Subtract two electrons for each bond from the total number of valence electrons.
  • Distribute the remaining electrons around their remaining atoms in such a manner as to best satisfy each atom
  • Electrons that are not involved in bonding should be shown as lone pairs by drawing a single dot for each electron.
  • At this point, identify if all of the atoms that are satisfied. (note: the octet rule only applies 100% for C/N/O/F)
  • If there are too few electrons to satisfy every atom, replace one single bond with a double bond on the unsatisfied atoms.
  • If your species is a polyatomic ion, put square brackets around your Lewis structure and place the overall charge of the ion on the outside of the square brackets.
  • If your compound is ionic, then take electrons from the metal and move them to the non-metal. Draw brackets around each separately, with the appropriate charge on each.

Practice

  • NCl3
  • OCS
  • H2O2
  • C2H3O2-1

Homework

  • Ch. 9 (43 – 46)
  • Note: determine formal charge of each atom

Information

This entry was posted on January 10, 2013 by in CAgenda, Chemistry and tagged , .

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