1. Chapter 8 “Covalent Bonding”

24. - Page 215 These are some of the different ways to represent ammonia: 1. The molecular formula shows how many atoms of each element are present 2. The structural formula ALSO shows the arrangement of these atoms! 3. The ball and stick model is the BEST , because it shows a 3-dimensional arrangement.

59. Other Structural Examples H C N C O H H

66. Resonance in Ozone Neither structure is correct, it is actually a hybrid of the two. To show it, draw all varieties possible, and join them with a double-headed arrow. Note the different location of the double bond

68. Polyatomic ions – note the different positions of the double bond. Resonance in a carbonate ion (CO 3 2- ): Resonance in an acetate ion (C 2 H 3 O 2 1- ):

75. - Pages 230 and 231 Sigma bond is symmetrical along the axis between the two nuclei. Pi bond is above and below the bond axis, and is weaker than sigma

81. - Page 232 Methane has an angle of 109.5 o , called tetrahedral Ammonia has an angle of 107 o , called pyramidal Note the unshared pair that is repulsion for other electrons.

89. Table of Electronegativities Higher electronegativity

100. #2. Dipole Interactions                                

104. Hydrogen Bonding (Shown in water) This hydrogen is bonded covalently to: 1) the highly negative oxygen, and 2) a nearby unshared pair. H H O  +  -  + H H O  +  -  +

105. Hydrogen bonding allows H 2 O to be a liquid at room conditions. H H O H H O H H O H H O H H O H H O H H O

108. Covalent Network Compounds Some covalently bonded substances DO NOT form discrete molecules. Diamond, a network of covalently bonded carbon atoms Graphite, a network of covalently bonded carbon atoms

109. End of Chapter 8