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8 Chemical Bonding Solutions to Exercises (b) Electronegativity is the ability of an atom in a molecule to attract electrons to itself. It can be thought of as the ability to hold its own electrons (as measured by ionization energy) and the capacity to attract the electrons of other atoms (as measured by electron affinity). Thus, both properties are relevant to the concept of electronegativity. (c) EN = k(IE - EA). For F: 4.0 = k(2009), k = 4.0/2009 = 2.0 X (d) Cl: EN = 2.0 X 10⁻³ (1600) = 3.2 O: EN = 2.0 10⁻³ (1314 - (-141)) = 2.9 These values do not follow the trend on Figure 8.7. The Pauling scale on the figure shows O to be second only to F in electronegativity, more electronegative than Cl. The simple definition EN = k(IE - EA) that employs thermochemical properties of isolated, gas phase atoms does not take into account the complex bonding environment of molecules. 8.106 (a) Assume 100 g. 1mol = 1.209 mol C; / 1.209 = 1 1 mol = 1.816 mol H; 1.816 1.209 = 1.5 64.30 g 35.453 1 mol = 1.814 mol Cl; = 1.5 1 mol = 1.209 mol O; / 1.209 = 1.0 Multiplying by 2 to obtain an integer ratio, the empirical formula is (b) The empirical formula mass is 2(12.0) + 3(1.0) + 3(35.5) + 2(16) = 165.5. The empirical formula is the molecular formula. (c) 44 22 pairs C H 8.107 (a) Assume 100 g. 1 mol 62.04 g Ba = 0.4518 mol Ba; 0.4518 0.4518 = 1.0 Ba 1 mol =2.710 mol N; 0.4518 = 6.0 The empirical formula is BaN₆. Ba has an ionic charge of 2+, so there must be two 1- azide ions to balance the charge. The formula of each azide ion is N₃⁻. 225