Chapter 3 - Exercises - Page 150e: 86

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To draw the Lewis structures for the given compounds ($SF_6$, $ClF_5$, and $XeF_4$) whose central atoms do not follow the octet rule, we need to consider the valence electron configurations of the central atoms and the overall geometry of the molecules. 1. $SF_6$ (Sulfur Hexafluoride): Lewis structure: ``` F-S-F | | F-S-F | | F-S-F ``` Explanation: - The central atom is sulfur (S), which has a valence electron configuration of 3s^2 3p^4, giving it a total of 6 valence electrons. - To form the $SF_6$ molecule, the sulfur atom forms six covalent bonds with six fluorine atoms, each contributing one electron to the bond. - The resulting structure has a total of 12 bonding electrons (6 bonds × 2 electrons per bond) and 6 lone pair electrons on the sulfur atom. - The overall geometry of the molecule is octahedral, with the six fluorine atoms arranged around the central sulfur atom. 2. $ClF_5$ (Chlorine Pentafluoride): Lewis structure: ``` F-Cl-F | | F-Cl-F ``` Explanation: - The central atom is chlorine (Cl), which has a valence electron configuration of 3s^2 3p^5, giving it a total of 7 valence electrons. - To form the $ClF_5$ molecule, the chlorine atom forms five covalent bonds with five fluorine atoms, each contributing one electron to the bond. - The resulting structure has a total of 10 bonding electrons (5 bonds × 2 electrons per bond) and 2 lone pair electrons on the chlorine atom. - The overall geometry of the molecule is trigonal bipyramidal, with the five fluorine atoms arranged around the central chlorine atom. 3. $XeF_4$ (Xenon Tetrafluoride): Lewis structure: ``` F-Xe-F | | F-Xe-F ``` Explanation: - The central atom is xenon (Xe), which has a valence electron configuration of 5s^2 5p^4, giving it a total of 8 valence electrons. - To form the $XeF_4$ molecule, the xenon atom forms four covalent bonds with four fluorine atoms, each contributing one electron to the bond. - The resulting structure has a total of 8 bonding electrons (4 bonds × 2 electrons per bond) and 2 lone pair electrons on the xenon atom. - The overall geometry of the molecule is square planar, with the four fluorine atoms arranged around the central xenon atom. In all three cases, the central atoms do not follow the octet rule, as they have more or fewer than 8 valence electrons. This is due to the ability of these atoms to accommodate more or fewer than 8 electrons around them, which is a result of their specific electronic configurations and the nature of the chemical bonds formed.