Ch.9 - Bonding & Molecular StructureWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Sections
Chemical Bonds
Lattice Energy
Lattice Energy Application
Born Haber Cycle
Dipole Moment
Lewis Dot Structure
Octet Rule
Formal Charge
Resonance Structures
Additional Practice
Bond Energy

Lattice Energy is the energy required to combine gaseous ions into a solid, crystalline structure. 

Examining Lattice Energy

Concept #1: Understanding Exergonic & Endergonic Reactions 

When dealing with the absorbing or releasing of energy in general then we use the terms endergonic & exergonic

Concept #2: Understanding Lattice Energy

Example #1: For each pair, choose the compound with the lower lattice energy.

a. BaO or MgO

b. LiCl  or  CaS

Practice: Choose the compound with the lower lattice energy.

Practice: Choose the compound with the higher lattice energy.

Additional Problems
Which is a FALSE statement? (A) The lattice energy of LiCl has a larger magnitude than that of NaCl. (B) The lattice energy of CaO has a larger magnitude than that of NaCl. (C) Na reacts with 1/2 Cl 2 to form NaCl molecules (D) Some ionic compounds may not conduct electricity when dissolved in water. (E) Lattice energy decreases as ionic radius increases as long as charge remains constant.
The lattice energy for ionic crystals decreases as the charge on the ions _____________ and the size of the ions __________________.  (a) increases, increases (b) increases, decreases (c) decreases, increases (d) decreases, decreases (e) None of these choices are correct.
Which of the following ionic bonds will have the greatest attraction? A. BeCl2 B. MgCl2 C. SrCl2 D. BaCl2
Consider the following ionic substances and arrange them in order of decreasing lattice energy. MgCl2            CaCl 2            MgF 2 A.  MgF2>CaCl2>MgCl2  B. MgF2>MgCl2>CaCl2 C. MgCl2>CaCl2>MgF2 D. CaCl2>MgF2>MgCl2 E. CaCl2>MgCl2>MgF2
Which of the following compounds would be expected to have the greatest lattice energy? a) SrO b) CsI c) NaBr d) MgO e) BaS
Which of the following reactions is associated with the  lattice energy of Li2O (ΔH°latt)? a) Li2O (s)  →  2 Li+ (g) + O2- (g) b) 2 Li+ (aq) + O2- (aq)  →   Li2O (s) c) 2 Li+ (g) + O2- (g) →    Li2O (s) d) Li2O (s) →   2 Li+ (aq) +  O2- (aq) e) 2 Li (s) + O2 (g) →  Li2O (s)
Choose the situation below that would result in an exothermic ΔH solution. A) When |ΔHlattice| is close to |ΔH hydration| B) When |ΔHsolvent | >> |ΔHsolute| C) When |ΔHlattice| < |ΔH hydration| D) When |ΔHlattice| > |ΔH hydration| E) There isnʹt enough information to determine
Predict the reaction associated with lattice energy, ΔHlat of BaS.
The lattice energy of calcium bromide is the energy change for the reaction 1. CaBr2(s) → Ca(g) + 2 Br(g) 2. Ca(s) + Br2(ℓ) → CaBr 2(s) 3. Ca(g) + 2 Br(g) → CaBr 2(g) 4. CaBr2(s) → Ca2+(g) + 2 Br−(g) 5. CaBr2(s) → Ca(g) + Br 2(g)
Which of the following solids would have the highest melting point? 1) NaI 2) NaF 3) MgO 4) MgCl2 5) KF
Choose the compound below that should have the highest melting or boiling point according to the ionic bonding model. AIN                                   MgO                                   NaF             
Which statement is a FALSE statement? a. The lattice energy of LiCl has a larger magnitude than that of NaCl. b. The lattice energy of CaO has a larger magnitude that that of NaCl. c. Na reacts with ½ Cl 2 to form NaCl molecules. d. Some ionic compounds may not conduct electricity when dissolved in water. e. Lattice energy decreases as ionic radius increases as long as charge remains constant.
Place the following in order of decreasing magnitude of lattice energy. KCl        MgO       RbI a. RbI > KCl > MgO b. RbI > MgO > KCl c. MgO > RbI > KCl d. MgO > KCl > RbI 
Which of the following compounds is expected to have the strongest ionic bond? a. MgO b. KBr c. NaI d. SrO e. CaS
Which of the following would have the highest melting point? 1. KF 2. KBr 3. Kl 4. KCl 5. RbF
The lattice enthalpy of calcium oxide is the energy change for the reaction 1. CaO(s) → Ca(g) + ½ O2(g) 2. Ca(g) + ½ O2(g) → CaO(s) 3. Ca(g) + O(g) → CaO(g) 4. CaO(s) → Ca2+(g) + O2- (g) 5. CaO(s) → Ca(g) + O(g)
If the following crystallize in the same type of structure, which has the highest lattice energy? 1. KF 2. KBr 3. KCl 4. LiF 5. LiCl
The solubilities of NaF and NaCl in water at 25°C are approximately 360 g/L H 2O and 80 g/L H2O respectively. Based on this information, which compound do you think has the larger lattice energy? 
The reaction of Fe2O3(s) with Al(s) to form Al2O3(s) and Fe(s) is called the thermite reaction and is highly exothermic.What role does lattice energy play in the exothermicity of the reaction?
Illustrated are four ions - A, B, X, and Y - showing their relative ionic radii. The ions shown in red carry positive charges: a 2+ charge for A and a 1+ charge for B. Ions shown in blue carry negative charges: a 1- charge for X and a 2- charge for Y.Among those combinations, which leads to the ionic compound having the largest lattice energy?
A portion of a two-dimensional "slab" of NaCl(s) is shown here in which the ions are numbered. Consider ion 5. How many attractive electrostatic interactions are shown for it?
A portion of a two-dimensional "slab" of NaCl(s) is shown here in which the ions are numbered. Is the sum of the attractive interactions in part (c) larger or smaller than the sum of the repulsive interactions in part (d)?
A portion of a two-dimensional "slab" of NaCl(s) is shown here in which the ions are numbered. If this pattern of ions was extended indefinitely in two dimensions, would the lattice energy be positive or negative?
What is lattice energy?
How does lattice energy relate to ionic radii?
How does lattice energy relate to ion charge?
Consider the lattice energies of the following Group 2A compounds: BeH2, 3205 kJ/mol; MgH2, 2791 kJ/mol; CaH2, 2410 kJ/mol; SrH2, 2250 kJ/mol; BaH2, 2121 kJ/mol.What is the oxidation number of H in these compounds?
The ionic compound CaO crystallizes with the same structure as sodium chloride. Would energy be consumed or released if a crystal of CaO was converted to a collection of widely separated Ca-O ion pairs?
The ionic compound CaO crystallizes with the same structure as sodium chloride. How does the potential energy compare to the lattice energy of CaO?
Use the ionic bonding model to determine which has the higher melting point, NaCl or MgO.
Reaction of sodium metal with chlorine gas to form the ionic compound sodium chloride.Do you expect a similar reaction between potassium metal and elemental bromine?
Which of the following statements concerning lattice energy is false?a. The lattice energy for a solid with 2+ and 2- ions should be two times that for a solid with 1- and 1- ions. b. MgO has a larger lattice energy than NaF. c. MgO has a larger lattice energy than LiF. d. It is often defined as the energy released when an ionic solid forms from its ions. e. All of these are true.
Rank this series of ionic compounds from smallest to largest magnitude (most exothermic) lattice energy:  NaCl         MgO        CaO       Al  2O3  a. NaCl < CaO < MgO < Al 2O3b. CaO < NaCl < MgO < Al 2O3c. Al2O3 < CaO < NaCl < MgOd. CaO < NaCl < Al 2O3 < MgOe. Al2O3 < NaCl < CaO < MgO 
A) Arrange the following substances in order of decreasing magnitude of lattice energy. CaO, NaF, SrO, KCl Rank from largest to smallest magnitude of lattice energy. B) Draw each molecule with their atoms and bonds NF3, HBr, SBr2, CCl4
The lattice energy of LiF is 1023 kJ/mol, and the Li–F distance is 200.8 pm. NaF crystallizes in the same structure as LiF but with a Na–F distance of 231 pm. Which of the following values most closely approximates the lattice energy of NaF: 510, 890, 1023, 1175, or 4090 kJ/mol? Explain your choice.
The lattice energy of LiF is 1023 kJ/mol, and the Li–F distance is 201 pm. MgO crystallizes in the same structure as LiF but with a Mg–O distance of 205 pm. Which of the following values most closely approximates the lattice energy of MgO: 256 kJ/mol, 512 kJ/mol, 1023 kJ/mol, 2046 kJ/mol, or 4008 kJ/mol? Explain your choice.
Does the lattice energy of an ionic solid increase or decrease as the charges or sizes of the ions increase?
In the equation Hsoln = Hsolute + Hsolvent + Hmix, which of the energy terms for dissolving an ionic solid would correspond to the lattice energy?
Although Al(OH)3 is insoluble in water, NaOH is very soluble. Explain in terms of lattice energies.
Compare the electron affinity of fluorine to the ionization energy of sodium. Does the process of an electron being “pulled” from the sodium atom to the fluorine atom have a negative or a positive ΔE? Why is NaF a stable compound? Does the overall formation of NaF have a negative or a positive ΔE? How can this be?
If you were to perform the reaction KCl (s) →  K+(g)+ Cl–(g), would energy be absorbed or released?Lattice Energies for Some Ionic CompoundsCompoundLattice Energy(kJ/mol)CompoundLattice Energy(kJ/mol)LiF1030MgCl22326LiCl834SrCl22127LiI730NaF910MgO3795NaCl788CaO3414NaBr732SrO3217NaI682KF808ScN7547KCl701KBr671CsCl657CsI600
The lattice energy of CsF is -744 kJ/mol, whereas that of BaO is -3029 kJ/mol. Explain this large difference in lattice energy.
Is lattice energy usually endothermic or exothermic?
For each of the following, write an equation that corresponds to the energy given.a. lattice energy of NaCl
Write the chemical equation that represents the process of lattice energy for the case of NaCl.
For each of the following, write an equation that corresponds to the energy given.b. lattice energy of NH4Br
Consider the lattice energies of the following Group 2A compounds: BeH 2, 3205 kJ/mol; MgH2, 2791 kJ/mol; CaH2, 2410 kJ/mol; SrH2, 2250 kJ/mol; BaH2, 2121 kJ/mol.Consider BeH2. Does it require 3205 kJ of energy to break one mole of the solid into its ions, or does breaking up one mole of solid into its ions release 3205 kJ of energy?
Consider the lattice energies of the following Group 2A compounds: BeH 2, 3205 kJ/mol; MgH2, 2791 kJ/mol; CaH2, 2410 kJ/mol; SrH2, 2250 kJ/mol; BaH2, 2121 kJ/mol.The lattice energy of ZnH2 is 2870 kJ/mol. Considering the trend in lattice enthalpies in the Group 2A compounds, predict which Group 2A element is most similar in ionic radius to the Zn2+ ion.
For each of the following, write an equation that corresponds to the energy given.c. lattice energy of MgS
Consider the ionic compounds KF, NaCl, NaBr, and LiCl. Use ionic radii (from the figure below) to estimate the cation–anion distance for each compound. Based on your answers, arrange these four compounds in order of decreasing lattice energy.Check your predictions with the experimental values of lattice energy from the table. Are the predictions from ionic radii correct?
Which of the following trends in lattice energy is due to differences in ionic radii?(a) NaCl > RbBr > CsBr(b) BaO > KF(c) SrO > SrCl2
The ionic compound CaO crystallizes with the same structure as sodium chloride.Calculate the energy of a mole of Ca—O ion pair that is just touching. How does this compare to the lattice energy of CaO?What factor do you think accounts for most of the discrepancy between the energies earlier–the bonding in CaO is more covalent than ionic, or the electrostatic interactions in a crystal lattice are more complicated than those in a single ion pair?
An ionic substance of formula MX has a lattice energy of 6 x 103 kJ/mol. Is the charge on the ion M likely to be 1+, 2+ or 3+?
Use principles of atomic structure to answer each of the following:(b) The lattice energy of CaO(s) is –3460 kJ/mol; the lattice energy of K2O is –2240 kJ/mol. Account for the difference.
Geologists have a rule of thumb: when molten rock cools and solidifies, crystals of compounds with the smallest lattice energies appear at the bottom of the mass. Suggest a reason for this.
Rank the compounds in order of decreasing magnitude of lattice energy. From Largest to Smallest BaO, KCl, CaO, RbBr
For which of the following substances is the least energy required to convert one mole of the solid into separate ions?(a) MgO(b) SrO(c) KF(d) CsF(e) MgF2
Based on the lattice energies of MgCl2 and SrCl2 given in Table 8.1 in the textbook, what is the range of values that you would expect for the lattice energy of CaCl2?
Arrange the following substances not listed in the table according to their expected lattice energies, listing them from highest lattice energy to the lowest: MgS, KI, GaN, LiBr.
Which compound of the following pair of ionic substance has the most negative lattice energy? Justify your answer.a. NaCl, KCl
Which compound in each of the following pairs has the larger lattice energy? Explain your choices.(a) MgO or MgSe
Which compound of the following pair of ionic substance has the most negative lattice energy? Justify your answer.c. BaCl2, BaO
Which compound in each of the following pairs has the larger lattice energy? Note: Mg2+ and Li+ have similar radii. Explain your choices.(d) Li2Se or MgO
Which compound in each of the following pairs has the larger lattice energy? Explain your choices.(a) K2O or Na2O
Which compound in each of the following pairs has the larger lattice energy? Note: Ba2+ and K+ have similar radii; S2– and Cl– have similar radii. Explain your choices.(c) KCl or BaS
Which of the following compounds requires the most energy to convert one mole of the solid into separate ions?(a) MgO(b) SrO(c) KF(d) CsF(e) MgF2
Which of the following compounds requires the most energy to convert one mole of the solid into separate ions?(a) K2S(b) K2O(c) CaS(d) Cs2S(e) CaO
Arrange the compounds in order of decreasing magnitude of lattice energy: LiBr, KI, and CaO.
Which compound has the highest magnitude of lattice energy?a) MgSb) CaSc) SrSd) BaS
Which set of compounds is arranged in order of increasing magnitude of lattice energy?a) CsI < NaCl < MgSb) NaCl < CsI < MgSc) MgS < NaCl < CsId) CsI < MgS < NaCl
Which compound has a higher magnitude lattice energy: NaCl or MgCl2?
For the following pair, choose the compound with the larger lattice energy, and explain your choice:BaS or CsCl
For the following pair, choose the compound with the larger lattice energy, and explain your choice:BaO or SrO
The radii of the lithium and magnesium ions are 76 pm and 72 pm, respectively. Which compound has stronger ionic attractions, lithium oxide or magnesium oxide?
Arrange these compounds in order of increasing magnitude of lattice energy: KCl, SrO, RbBr, CaO.
From the following ions (with their radii in pm), choose the pair that forms the strongest ionic bond and the pair that forms the weakest:Ion:           Mg2+     K+     Rb+     Ba2+     Cl−     O2−     I−Radius:     72      138    152      135     181     140    220
The substances NaF and CaO are isoelectronic (have the same number of valence electrons).Without looking up lattice energies, which compound is predicted to have the larger lattice energy?
Consider the ionic compounds KF, NaCl, NaBr, and LiCl. Use ionic radii (from the figure below) to estimate the cation–anion distance for each compound. Based on your answers, arrange these four compounds in order of decreasing lattice energy.
Based on the lattice energy trends, put the following ionic compounds in order from lowest melting point to highest melting point.CaO     MgO     SrSa. SrS < CaO < MgOb. CaO < SrS < MgOc. MgO < CaO < SrSd. SrS < MgO < CaOe. CaO < MgO < SrS
Of the compounds below, which exhibits the most ionic character?(1) RbCl (2) LiI (3) BF3 (4) ZnCl2 (5) BaI2
Which compound in each of the following pairs has the larger lattice energy? Note: Mg2+ and Li+ have similar radii; O2– and F– have similar radii. Explain your choices.(b) LiF or MgO
A portion of a two-dimensional "slab" of NaCl(s) is shown here in which the ions are numbered.Consider ion 5. How many repulsive interactions are shown for it?
Of the compounds below, __________ has the smallest ionic separation.A) KFB) K2SC) RbClD) SrBr2E) RbF
Place the following in order of Increasing magnitude of lattice energy.MgO NaI BaOa. Nal < MgO < BaOb.  MgO < Nal < BaOc. MgO < BaO < Nald. BaO < MgO < Nale. Nal < BaO < MgO 
Which of the following has the highest lattice energy?NaClKIMgOBaOCaO
Which of these ionic solids would have the largest magnitude lattice energy?A. KF      B. CaBr2      C. NaF      D. MgO      E. CaI2
Consider the following trend in the lattice energies of the alkaline earth metal oxides:Metal OxideLattice Energy (kJ/mol)MgO-3795CaO-3414SrO-3217BaO-3029Explain this trend.
Rubidium iodide has a lattice energy of -617 kJ/mol, while potassium bromide has a lattice energy of -671 kJ/mol.Why is the lattice energy of potassium bromide more exothermic than the lattice energy of rubidium iodide?
Which of the following has the highest melting point?RbFKIKFKBrKCl
Which of the following ionic solids have the largest magnitude lattice energy?A. NaF B. CaCl2 C. CaBr2 D. CaOE. NaCl
The chloride of which of the following metals should have the greatest lattice energy?A) potassiumB) rubidiumC) sodiumD) lithiumE) cesium
Which metal has the lowest melting point?a) Lib) Nac) Kd) Rb
Which of the following has the lowest melting point?(A) H2O (B) KBr (C) LiF (D) Kr (E) Ne
Arrange the following binary ionic compounds in order of decreasing melting point.a. MgS, NaBr, MgBr2b. MgS, MgBr2, NaBrc. NaBr, MgBr2, MgSd. MgBr2, NaBr, MgS,e. NaBr, MgS, MgBr2
For the following pair, choose the compound with the larger lattice energy, and explain your choice:CaO or CaS
The lattice energy of KF is 794 kJ/mol, and the interionic distance is 269 pm. The Na–F distance in NaF, which has the same structure as KF, is 231 pm. Which of the following values is the closest approximation of the lattice energy of NaF: 682 kJ/mol, 794 kJ/mol, 924 kJ/mol, 1588 kJ/mol, or 3175 kJ/mol? Explain your answer.
Aluminum oxide (Al2O3) is a widely used industrial abrasive (known as emery or corundum), for which the specific application depends on the hardness of the crystal. What does this hardness imply about the magnitude of the lattice energy? Would you have predicted from the chemical formula that Al2O3 is hard? Explain.
Rationalize the following lattice energy values:
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?
The lattice energies of FeCl3, FeCl2, and Fe2O3 are (in no particular order) -2631, -5359, and -14,774 kJ/mol. Match the appropriate formula to each lattice energy. Explain.
Periodic trends in lattice energy as a function of cation or anion radius.Using this figure, can you place an upper and lower limit on the lattice energy of KF?
Rank the following ionic compounds by the magnitude of their lattice energy. Rank from highest to lowest magnitude of lattice energy.LiCl, MgO, Na2O, BeO, Na2O