CHAPTER ONE Chemical Bonding PROBLEM 1.9 Like nitric acid, each of the following inorganic compounds will be frequently encountered in this text. Calculate the formal charge on each of tructures gIv H--S—0-H SAMPLE SOLUTION (a)The formal charge is the difference between the num- ber of valence electrons in the neutral atom and the electron count in the lewis structure.(The number of valence electrons is the same as the group number in the periodic table for the main-group elements. Valence electrons of neutral atom Electron count Formal charge Sulfur: 667 4(6)+2=5 4(2)+6=7 chlorine 4(2)+6=7 The formal charges are shown in the Lewis structure of thionyl chloride Cl-S-CI So far we've only considered neutral molecules--those in which the sums of the positive and negative formal charges were equal. with ions, of course, these sums will not be equal. Ammonium cation and borohydride anion, for example, are ions with net harges of +I and -l, respectively. Nitrogen has a formal charge of +I in ammonium ion, and boron has a formal charge of -l in borohydride. None of the hydrogens in the Lewis structures shown for these ions bears a formal charge H HH—B-H H Ammonium ion Borohydride ion PROBLEM 1.10 Verify that the formal charges on nitrogen in ammonium ion and boron in borohydride ion are as shown Formal charges are based on Lewis structures in which electrons are considered to be shared equally between covalently bonded atoms. Actually, polarization of N-H bonds in ammonium ion and of B-H bonds in borohydride leads to some transfer of positive and negative charge, respectively, to the hydrogens PROBLEM 1.11 Use 8+ and 8- notation to show the dispersal of charge to the hydrogens in NHa and BHa Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsitePROBLEM 1.9 Like nitric acid, each of the following inorganic compounds will be frequently encountered in this text. Calculate the formal charge on each of the atoms in the Lewis structures given. SAMPLE SOLUTION (a) The formal charge is the difference between the num￾ber of valence electrons in the neutral atom and the electron count in the Lewis structure. (The number of valence electrons is the same as the group number in the periodic table for the main-group elements.) The formal charges are shown in the Lewis structure of thionyl chloride as Cl±S±Cl O W   Sulfur: Oxygen: Chlorine: Valence electrons of neutral atom 6 6 7 Formal charge
1 1 0 Electron count 1 2(6)
2 5 1 2(2)
6 7 1 2(2)
6 7 Cl±S±Cl O W (a) Thionyl chloride H±O±S±O±H O W W O (b) Sulfuric acid H±O±NœO (c) Nitrous acid 18 CHAPTER ONE Chemical Bonding So far we’ve only considered neutral molecules—those in which the sums of the positive and negative formal charges were equal. With ions, of course, these sums will not be equal. Ammonium cation and borohydride anion, for example, are ions with net charges of 1 and 1, respectively. Nitrogen has a formal charge of 1 in ammonium ion, and boron has a formal charge of 1 in borohydride. None of the hydrogens in the Lewis structures shown for these ions bears a formal charge. PROBLEM 1.10 Verify that the formal charges on nitrogen in ammonium ion and boron in borohydride ion are as shown. Formal charges are based on Lewis structures in which electrons are considered to be shared equally between covalently bonded atoms. Actually, polarization of N±H bonds in ammonium ion and of B±H bonds in borohydride leads to some transfer of positive and negative charge, respectively, to the hydrogens. PROBLEM 1.11 Use  and  notation to show the dispersal of charge to the hydrogens in NH4  and BH4 . Ammonium ion H±N±H H W W H  Borohydride ion H±B±H H W W H  Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website