CHE-121 - WA #9 - 2016 November CHE-121-OL009 Written Assignment#9 Kevin D Hargett 1 Use the second member of each group from Group IA to Group 7A to

CHE-121 - WA #9 - 2016 November CHE-121-OL009 Written...

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2016 November CHE-121-OL009 Written Assignment #9 Kevin D. Hargett 1. Use the second member of each group from Group IA to Group 7A to show that the number of valence electrons on an atom of the element is the same as its group number. (8 points) (Reference: Chang 9.2) The second member of group 1A is Na, has one valence electron. The second member of group 2A is Mg, has two valence electrons. The second member of group 3A is Al, has three valence electrons. The second member of group 4A is Si, has four valence electrons. The second member of group 5A is P, has five valence electrons. The second member of group 6A is S, has six valence electrons. The second member of group 7A is Cl, has seven valence electrons. 2.Explain the following: (3 points) a. ionic bond: the electrostatic force that chemically links two oppositely-charged ions. Ionic bonds contain a difference greater than 2.0 eV between the atoms. b. nonpolar covalent bond: a bond between atoms where electrons are shared. NPC bonds contain a difference below 0.4 eV between the atoms. c. polar covalent bond: a bond between atoms where electrons that have different charges unevenly share electrons. PC bonds contain a difference between 0.4 eV and 2.0 eV between the atoms. 3. Specify which compound in the following pairs of ionic compounds has the higher lattice energy: Explain your choice. (6 points) (Reference: Chang 9.23) a. KCl or MgO: MgO has higher charged ions (+2) resulting in a higher attraction force and thus a more stable atom b. LiF or LiBr: LiF LiF has similar atomic radii meaning a more stable atomic structure. LiBr is weaker than LiF.
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