Major Points*Chemical bonds hold groups of atoms together. They can be classified into several types. An ionic bond is formed when a transfer of electrons occurs to form ions; in a purely covalent bond, electrons are shared equally between identical atoms. Between these extremes lies the polar covalent bond, in which electrons are shared unequally between atoms with different electronegativities.
*Electronegativity is defined as the relative ability of an atom in a molecule to attract the electrons shared in a bond. *Lewis structures are drawn to represent the arrangement of the valence electrons in a molecule. *Some molecules have more than one valid Lewis structure, a property called resonance. *The molecular structure of a molecule describes how the atoms are arranged in space. *The molecular structure of a molecule can be predicted by using the valence shell electron pair repulsion model. Online ResourcesLewis Dot Structure:
http://cnx.org/content/m38701/latest/ VSEPR theory: http://cnx.org/content/m31949/latest/ VideosLewis Dot:
http://www.youtube.com/watch?v=ulyopnxjAZ8 VSEPR theory: http://www.youtube.com/watch?v=qvPKWcXdo7Y&feature=related Activity
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Example Calculations1. Find valence electrons for H2O
H=2x1=2 O=1x6=6 2+6=8 valence electrons 2. find valence electrons for NH3 N=1x5=5 H=3x1=3 5+3=8 valence electrons 3. find valence electrons for PCl3 P=1x5=5 Cl=3x7=21 5+21=26 valence electrons 4. find valence electrons for CH4 C=1x4=4 H=4x1=4 4+4=8 valence electrons 5. find valence electrons for CO2 C=1x4=4 O=2x6=12 4+12=16 valence electrons 6. do the Lewis Dot structure for OH-
7. do the Lewis dot structure for Na2O
8. do the Lewis dot structure for O2
9. do the Lewis dot structure for H
10. Do the Lewis Dot structure for MgCl2
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