Write the electron configuration for each of the following ions, and determine which ones possess noble-gas configurations: (a) Be2+, (b) Mn2+, (c) Cd2+, (d) Fe3+, (e) Tl+, (f) At-.

(a) Is lattice energy usually endothermic or exothermic?

(b) Write the chemical equation that represents the process of lattice energy for the case of NaCl.

(c) Would you expect salts like NaCl, which have singly charged ions, to have larger or smaller lattice energies compared to salts like CaO which are composed of doubly-charged ions?

NaCl and KF have the same crystal structure. The only difference between the two is the distance that separates cations and anions. (a) The lattice energies of NaCl and KF are given in Table 8.1. Based on the lattice energies, would you expect the Na─Cl or the K─F distance to be longer?

NaCl and KF have the same crystal structure. The only difference between the two is the distance that separates cations and anions. (b) Use the ionic radii given in Figure 7.8 to estimate the Na─Cl and K─F distances.

The substances NaF and CaO are isoelectronic (have the same number of valence electrons). (a) What are the charges on each of the cations in each compound?

The substances NaF and CaO are isoelectronic (have the same number of valence electrons). (b) What are the charges of each of the anions in each compound?

The substances NaF and CaO are isoelectronic (have the same number of valence electrons). (c) Without looking up lattice energies, which compound is predicted to have the larger lattice energy?

The substances NaF and CaO are isoelectronic (have the same number of valence electrons). (d) Using the lattice energies in Table 8.1, predict the lattice energy of ScN.

(a) Does the lattice energy of an ionic solid increase or decrease (i) as the charges of the ions increase, (ii) as the sizes of the ions increase?

(b) Arrange the following substances not listed in Table 8.1 according to their expected lattice energies, listing them from lowest lattice energy to the highest: MgS, KI, GaN, LiBr.

Consider the ionic compounds KF, NaCl, NaBr, and LiCl. (a) Use ionic radii (Figure 7.8) to estimate the cation–anion distance for each compound.

Consider the ionic compounds KF, NaCl, NaBr, and LiCl. (b) Based on your answer to part (a), arrange these four compounds in order of decreasing lattice energy. (c) Check your predictions in part (b) with the experimental values of lattice energy from Table 8.1. Are the predictions from ionic radii correct?

Which of the following trends in lattice energy is due to differences in ionic radii? (a) LiF > NaF > CsF, (b) CaO > KCl, (c) PbS > Li2O.

Energy is required to remove two electrons from Ca to form Ca2+, and energy is required to add two electrons to O to form O2 - . Yet CaO is stable relative to the free elements. Which statement is the best explanation? (a) The lattice energy of CaO is large enough to overcome these processes. (b) CaO is a covalent compound, and these processes are irrelevant. (c) CaO has a higher molar mass than either Ca or O. (d) The enthalpy of formation of CaO is small. (e) CaO is stable to atmospheric conditions.

List the individual steps used in constructing a Born–Haber cycle for the formation of BaI₂ from the elements. Which of the steps would you expect to be exothermic?

(a) Based on the lattice energies of MgCl2 and SrCl2 given in Table 8.1, what is the range of values that you would expect for the lattice energy of CaCl2?

(b) Using data from Appendix C, Figure 7.11, Figure 7.13, and the value of the second ionization energy for Ca, 1145 kJ/mol, calculate the lattice energy of CaCl2.

(a) State whether or not the bonding in each substance is likely to be covalent: (i) glucose, (ii) nitrogen, (iii) aluminum hydroxide, (iv) ammonia, (v) neon.

(b) A substance, XY, formed from two different elements, melts at −33 °C. Is XY likely to be a covalent or an ionic substance?

Using Lewis symbols and Lewis structures, make a sketch of the formation of NCl₃ from N and Cl atoms, showing valence-shell electrons. (a) How many valence electrons does N have initially? (c) How many valence electrons surround the N in the NCl₃ molecule? (d) How many valence electrons surround each Cl in the NCl₃ molecule?

Using Lewis symbols and Lewis structures, make a sketch of the formation of NCl₃ from N and Cl atoms, showing valence-shell electrons. (b) How many bonds Cl has to make in order to achieve an octet?

Using Lewis symbols and Lewis structures, make a sketch of the formation of NCl₃ from N and Cl atoms, showing valence-shell electrons. (e) How many lone pairs of electrons are in the NCl₃ molecule?

Using Lewis symbols and Lewis structures, diagram the formation of PF₃ from P and F atoms, showing valence-shell electrons. (a) How many valence electrons does P have initially? (c) How many valence electrons surround the P in the PF₃ molecule? (d) How many valence electrons surround each P in the PF₃ molecule?

Using Lewis symbols and Lewis structures, diagram the formation of PF₃ from P and F atoms, showing valence-shell electrons. (e) Does PF₃ obey the octet rule?

(b) How many bonding electrons are in the structure?

(c) Would you expect the O—O bond in O₂ to be shorter or longer than the O—O bond in compounds that contain an O—O single bond? Explain.

(a) Construct a Lewis structure for hydrogen peroxide, H₂O₂, in which each atom achieves an octet of electrons.