11. Bonding & Molecular Structure

Lattice Energy

Lattice Energy of Ionic Compounds, Basic Introduction, Charge vs Ionic Radius

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?

Lattice Energy Example 1

The lattice energy for ionic crystals decreases as the charge of the ions _____ and the size of the ions _____.a) Increases, increases &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;b) Increases, decreases &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;c) Decreases, increases &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;d) Decreases, decreases

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.
(a) What is the oxidation number of H in these compounds?

Potassium nitrate has a lattice energy of -163.8 kcal>mol and a 
heat of hydration of -155.5 kcal>mol. How much potassium 
nitrate has to dissolve in water to absorb 1.00 * 102 kJ of heat?

A portion of a two-dimensional “slab” of NaCl(s) is shown 
here (see Figure 8.2) in which the ions are numbered. 
(d) Consider ion 5. How many 
repulsive interactions are shown for it? 
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/560412e0f7cea1eb-1664451423129.jpg" alt="" />

(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?

Lattice Energy Example 4

The lattice energy of CsF is -744 kJ>mol, whereas that of BaO is 
-3029 kJ>mol. Explain this large difference in lattice energy.

(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?

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.

Lattice Energies for Ionic Compounds

Larger Lattice Energy causes ionic bonds to be stronger. This in turn causes higher boiling and melting points, but lower solubility.

Understanding Lattice Energy

Which of the following compounds would you expect to have the highest boiling point?a) MgCl2b) SrOc) SrCl2d) CsIe) LiBr

Lattice Energy Summary in 4 Minutes (With Examples & Practice Problems)

The solubilities of CaCrO4 and PbCrO4 in water at 25°C are approximately 0.111 g/L and 0.0905 g/L in H2O respectively. Based on this information, which compound do you think has the smaller lattice energy?

NaCl has a lattice energy of -787 kJ>mol. Consider a hypothetical
salt XY. X3 + has the same radius of Na+ and Y3 - has the
same radius as Cl - . Estimate the lattice energy of XY.

Na (s) + &#189; Cl2 (g) &#8594; NaCl (s)

This reaction corresponds to the standard enthalpy of formation.

NaCl (s) &#8594; Na (g) + &#189; Cl2 (g)

The enthalpy of this reaction is &#8722;&#916;Hlattice

Na+ (g) + Cl&#x2212; (g) &#8594; NaCl (s)

Correct, the reaction shows the formation of the ionic solid from the component gaseous ions.

Cl (g) + e&#x2212; &#8594; Cl&#x2212; (g)

The energy involved in this reaction is the electron affinity.

2 Na (g) + Cl2 (g) &#8594; 2 NaCl (s)

The lattice energy involves gaseous ions.

 The lattice energy of an ionic compound is the energy associated with forming a crystal lattice of the compound from gaseous ions. 

Which of the following reactions has &#916;Hrxn = &#916;Hlattice?

Which of the following trends in lattice energy is due to differences
in ionic radii? (a) LiF 7 NaF 7 CsF, (b) CaO 7 KCl, (c) PbS 7 Li2O.

Lattice Dissociation Energy involves an endothermic&nbsp;process where energy is absorbed when ionic solid is broken up into gaseous ions.

Correct, KF represents the largest ions with the smallest charges.

There is another compound in which the charge on the ions is smaller and the size of the ions is larger.

It is not possible to empirically compare the lattice energies of these compounds.

The size and charge of the ions are valid criteria.

 Electrostatic forces depend on the magnitude of the charges and the distance between them. 

Which of the following should have the smallest magnitude for the lattice energy?

(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?

Lattice Formation Energy involves an exothermic&nbsp;process where energy is released when gaseous ions combine into ionic solid.

Use the data to calculate the heats of hydration of lithium chloride 
and sodium chloride. Which of the two cations, lithium or 
sodium, has stronger ion–dipole interactions with water? Why?
<TABLE>

Lattice Energies - Chemistry Tutorial

Sodium hydroxide (NaOH) has a lattice energy of -887 kJ>mol 
and a heat of hydration of -932 kJ>mol. How much solution 
could be heated to boiling by the heat evolved by the dissolution 
of 25.0 g of NaOH? (For the solution, assume a heat capacity 
of 4.0 J>g # °C, an initial temperature of 25.0 °C, a boiling 
point of 100.0 °C, and a density of 1.05 g>mL.)

Lattice Energy Example 3

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.
(b) Among the combinations in part (a), which leads to
the ionic compound having the largest lattice energy?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/ca6640a6dc42dc8c-1660921238558.jpg" alt="" />

Lattice Energy Example 2

Lattice Enthalpy and Enthalpy Changes | A-level Chemistry | OCR, AQA, Edexcel

Arrange these compounds in order of increasing magnitude of
lattice energy: KCl, SrO, RbBr, CaO.

Correct, the smallest alkaline earth ion will allow the ions to come the closest together.

The smallest alkaline earth ion will allow the ions to come the closest together.

Which of the following should have the largest magnitude for the 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.

The electron affinity of oxygen is -141 kJ>mol, corresponding
to the reaction
O1g2 + e-¡O-1g2
The lattice energy of K2O1s2 is 2238 kJ>mol. Use these data
along with data in Appendix C and Figure 7.10 to calculate
the “second electron affinity” of oxygen, corresponding to
the reaction
O-1g2 + e-¡O2 -1g2

Calculate the energy change in kilojoules per mole when lithium atoms lose an electron to bromine atoms to form isolated Li+ and Br-ions. [The Ei for Li1g2 is 520 kJ/mol; the Eea for Br1g2 is -325 kJ/mol.] Will a lithium atom transfer an elec-tron to a bromine atom to form isolated Li+ 1g2 and Br-1g2 ions? Explain.

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?

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?

Silver nitrate has a lattice energy of -820 kJ>mol and a heat of solution of 22.6 kJ>mol. Calculate the heat of hydration for silver nitrate.

Which of the following alkali metal halides has the largest lat-tice energy? Explain.
(a)  
(b) 
(c)

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Clutch Prep

1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Lewis Dot Structures: Neutral Compounds

Lewis Dot Structures or Electron Dot Structures&nbsp;are diagrams that show how elements in a molecule use their valence electrons to form bonds.&nbsp;

Average Bond Order

Average Bond Order represents the average number of chemical bonds between a pair of bond elements.

Lewis Dot Structures: Ions

Lewis Dot Structures of Ions involves losing or gaining valence electrons to draw the most likely structure.&nbsp;

Octet Rule

The&nbsp;Octet Rule states that main-group elements will generally form enough bonds to obtain 8 electrons in their valence shell.&nbsp;

Lewis Dot Symbols

Lewis Dot Symbols represent the outer shell electrons of an element.&nbsp;

Lewis Dot Structures: Sigma & Pi Bonds

Sigma Bonds directly connect element together, while Pi Bonds provide insulation and protection for those bonds.&nbsp;

Lewis Dot Structures: Exceptions

Lewis Dot Structure Exceptions&nbsp;happen when the central element violates the Octet Rule.

Born Haber Cycle

In the Born-Haber Cycle, ionic solids are created through the ionization and eventual combination of elements.&nbsp;

Coulomb's Law

Coulomb's Law is used to determine the forces experienced by charged particles.&nbsp;

Chemical Bonds

A chemical bond is the connection&nbsp;of different elements through the sharing, transferring or pooling of electrons.&nbsp;

Resonance Structures

Resonance Structures are used to represent the different possible bonding arrangements of a molecule.

Lewis Dot Structures: Acids

Drawing the Lewis Dot Structure of Acids&nbsp;involves first drawing the polyatomic anion and then attaching the H+ ion.&nbsp;

Formal Charge

Formal Charge is the charge given to an element within a molecule when assuming equal sharing of electrons between bonded elements.&nbsp;

Bond Energy

Bond Energy is the amount of energy stored within a chemical bond.

Lattice Energy&nbsp;is the estimate for the strength of ionic bonds.&nbsp;

Dipole Moment

Dipole arrows are used anytime a molecule possesses a dipole moment, which happens when a molecule is polar.&nbsp;