Lewis Dot Structures

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Lewis Dot Structures

• Covalent bonds The electron pairs are shared
  between atoms
• Ionic bond Electron(s) are transferred.
• The positive ion lost an electron
• The negative ion gained an electron

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Types of bonds
Covalent
Polar Covalent
Increased Ionic Character
Ionic
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Covalent Compounds
The same concept can be envisioned for other
covalent compounds
Think of the covalent bond as the electron
shared between the C and H atoms.
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Electronegativity Difference

• If the difference in electronegativities is
  between
• 1.7 to 4.0 Ionic
• 0.3 to 1.7 Polar Covalent
• 0.0 to 0.3 Non-Polar Covalent

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Ionic compounds exist as ions in a crystal lattice
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Charges of cations

• Group 1 Group 2 Group 13
• H Mg2 Al3
• Li Ca2
• Na Sr2
• K Ba2

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Answer the following

• A. Number of valence electrons in aluminum
• 1) 1 e- 2) 2 e- 3) 3 e-
• B. Change in electrons for octet
• 1) lose 3e- 2) gain 3 e- 3)
  gain 5 e-
• C. Ionic charge of aluminum
• 1) 3- 2) 5- 3) 3

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Anions gain electrons (nonmetals)

• Group 5 Group 6 Group 7
• N-3 O-2 F-1
• P-3 S-2 Cl-1

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Covalent Compounds

• Exist as molecules covalently bonded.

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VSEPR

• Valence Shell Electron Pair Repulsion theory.
• Electron pairs repell and are as far apart in
  three dimensional space as possible.

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Linear
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Trigonal Planar
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Trigonal planar Bond angle (120 oC)
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BentBond angle lt 120 o
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Tetrahedron
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Tetrahedron Bond angle 109.5o
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Trigonal Pyramidal
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Trigonal pyramidal Bond angle 107o
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BentBond angle 104.5o
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Draw the Lewis Electron dot structures for the
following

• H2S
• PH3
• AlBr3
• CCl4