Lewis Electron Dot Structure

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Lewis Electron Dot Structure
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Lewis electron dot structures

• Dots are placed around a symbol to indicate the
  number of valence e-
• Valence electrons are the outer shell electrons.

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Arranging the dots
2
6
X
3
5
1
7
4
8

• Dots can be rearranged to
• accommodate bonding illustration.

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Note that the arrangement of dots is the same
within each group.
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The Octet Rule
Octet Rule Atoms share, loose or gain electrons
when they react to have 8 electrons in their
outer shell. Hydrogen will only have 2
electrons. Helium only has 2 electrons Note
There are exceptions to the octet rule.
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Arranging the dots for an atom
H
Cl
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Arranging the dots for a molecule
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Arranging the dots and lines for a molecule
Replace bonding pairs with a line, but always
show the lone pairs of electrons.
Notice that each atom is obeying its proper
rule upon completion of the dot structure.
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Arranging the dots for water
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Final structure for water
H
O
H
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Arranging the dots forcarbon dioxide
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Arranging the dots forcarbon dioxide
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Arranging the dots forcarbon dioxide
C
O
O
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Final structure forcarbon dioxide
C
O
O
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Arranging the dots forcarbon monoxide
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Arranging the dots forcarbon monoxide
O
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Arranging the dots forcarbon monoxide
O
C
How many electrons does the oxygen have around
it?...the carbon?
Since O has 8 electrons, and C has four,
move electrons around to satisfy the octet rule.
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Arranging the dots forcarbon monoxide
O
C
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Final structure forcarbon monoxide
O
C
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Polyatomic ions OH1-
H
O
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OH1-

• Add brackets around the ion.

1-
H
O
Place the charge of the ion outside of the
brackets.
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OH1-

• So, where did the extra electron originate?

1-
H
O
Maybe a sodium atom was strolling byand donated
an electron to the cause.
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CO32-

• Carbon is the central atomit only appears one
  time.

C
Place four bonds around the central atom as
indicated by the Kelter Method, but you only have
3 perimeter atoms
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CO32-

• Attach the O atoms.

O
O
C
O
Make each O atom have 8 e-. Two O atoms
already have 2 e- and one O atom has 4 e- 6 dots
need to be added to two O atoms and 4 dots need
to be added to one O atom. Account for all owned
electrons.
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CO32-
2-

• Add brackets around the ion.

Place the charge of the ion outside of the
brackets.
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BI3

• Boron has three valence electrons
• This molecule is an example of an exception to
  the octet rule because the central atom will only
  have 6 electrons, not 8.

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BI3

• Boron is the central atomthere is no way only
  one bond can accommodate 3 Is!

B
Place the number of bonds around the central atom
that will take care of all of the perimeter atoms
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BI3

• Attach the perimeter I atoms.

Make each I atom happy with 8 e-. Each I atom
already has 2 e- 6 dots need to be added to each
I atom
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BeF2
Be
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Now, practice alot