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.

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Identify the concept of lattice energy, which is the energy required to separate one mole of an ionic solid into its gaseous ions.

Understand that lattice energy is influenced by the charge of the ions and the distance between them, which is related to the ionic radii.

Recall that smaller ionic radii result in stronger attractions between ions, leading to higher lattice energies.

Analyze the given options: (a) LiF > NaF > CsF, (b) CaO > KCl, (c) PbS > Li2O, and consider the ionic radii of the ions involved.

Determine which trend is primarily due to differences in ionic radii by comparing the sizes of the ions in each pair and how they affect the lattice energy.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Lattice Energy

Lattice energy is the amount of energy released when gaseous ions combine to form an ionic solid. It is a measure of the strength of the forces between the ions in an ionic compound. Higher lattice energy indicates stronger ionic bonds, which typically results in higher melting points and greater stability of the compound.

Ionic Radii

Ionic radii refer to the size of an ion in a crystal lattice. The size of the ions affects the distance between them; smaller ions can pack more closely together, leading to stronger electrostatic attractions and higher lattice energy. Conversely, larger ions result in greater distances and weaker attractions, thus lower lattice energy.

Trends in Lattice Energy

Trends in lattice energy can be observed based on the ionic sizes and charges of the ions involved. Generally, as the ionic radius decreases, the lattice energy increases due to stronger attractions between the ions. Additionally, higher charges on the ions also contribute to increased lattice energy, as the electrostatic forces become stronger.

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