UNIT VIII Lewis Structure Lesson 5. Lewis Structure.
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Transcript of UNIT VIII Lewis Structure Lesson 5. Lewis Structure.
UNIT VIIILewis Structure
Lesson 5
Lewis Structure
Gilbert Newton Lewis
Invented “Electron-dot” formulas or “Lewis Structures”
I’m so tired of writing all those useless inner
electrons, in the Bohring models!
Valence Electrons – electrons in the outermost occupied energy level. (s and p electrons outside the core)
Valence electrons can be represented by “dots” drawn around the atom.
Remember the rules…
VIII.3 CHEMICAL BONDING
C. Writing Lewis Structures
a. Simple Ionic Compounds:Draw the Lewis Structure of:
a) MgO
VIII.3 CHEMICAL BONDING
b)KCl
c) CaF2
VIII.3 CHEMICAL BONDING
b. Covalent Compounds:
Octet Rule: most atoms, other than hydrogen, tend to attain an octet of electrons as a result of forming covalent bonds
VIII.3 CHEMICAL BONDING
Rules:
1. Count the TOTAL # of valence e- (Subtract 1 e- for every positive charge, and add 1 e- for every negative charge on the molecule.)
2. Determine which atoms are bonded together, put 2 e- into each bond
3. Use the remaining valence e- to complete the octets of the atoms surrounding the central atom
4. If central atom has less than an octet of e-, have a neighbour share e- with the “deficient atom” by putting an extra pair of e-
5. Replace each pair of e- with a dash
VIII.3 BONDING
Ex. 1CH4
VIII.3 BONDING
Ex. 2NH4
+
VIII.3 BONDING
Ex. 3 O2
VIII.3 BONDING
Ex. 4 NO+
VIII.3 CHEMICAL BONDING
Ex. 5 CHO2
-
ONE LAST TO TRY
HPO2
HOMEWORK ON LEWIS STRUCTURE
Homework
p. 183 #85 p. 188 # 86a-u