Lewis Dot DiagramsLewis Dot Diagrams

• Show where electrons and bonds exist in covalent compounds.

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Lewis Dot DiagramsLewis Dot Diagrams

• Dots are used to show valence electrons for specific atoms.

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Lewis Dot DiagramsLewis Dot Diagrams

• Electrons are “shared” to form bonds and satisfy the octet rule.

• Example: H2O

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Lewis Dot DiagramsLewis Dot Diagrams

• Example: NH3

• 1st – Count up all valence electrons

• N = 5 e-

• H = 1 e- x 3 = 3 e-

• 8 total valence electrons

Lewis Dot DiagramsLewis Dot Diagrams

• 2nd – Draw individual dot diagrams

• Hint – place 1 per side to start.

N

HH H

Lewis Dot DiagramsLewis Dot Diagrams

• 3rd – Connect lone electrons to satisfy octet rule and form “bonds”

• Remember, H only wants 2 e- !

N

HH H

Lewis Dot DiagramsLewis Dot Diagrams

• Last Step – Draw a “final” picture with lines (2 shared electrons)

• Make sure that all valence electrons are accounted for!

• Any electrons that are not in bonds are called unshared, or lone pairs.

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8 Total Electrons!

Lewis Dot DiagramsLewis Dot Diagrams

• Some compounds will share more than 2 electrons, so multiple bonds are drawn.

• Example: O2

Each O has 8 e-

Double Bond

Lewis Dot DiagramsLewis Dot Diagrams

• Exceptions to the Octet Rule:

• Boron (6 e-)

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Lewis Dot DiagramsLewis Dot Diagrams

• Phosphorus (10 e-)

• Sulfur (12 e-)

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Lewis Dot DiagramsLewis Dot Diagrams

Too many valence electrons

Si not stable

Center H has too many e-

N not stable

What is wrong in the following diagrams?