Rationalize the following lattice energy values: Lattice Energy Compound (kJ / mo

step 1 Problem 67 says to rationalize the lattice energy values of each of these four compounds and dis

Rationalize the following lattice energy values: ...

Rationalize the following lattice energy values: $$ \begin{array}{|lc|} \hline & \text { Lattice Energy } \\ \text { Compound } & (\mathrm{kJ} / \mathrm{mol}) \\ \hline \mathrm{CaSe} & -2862 \\ \mathrm{Na}_{2} \mathrm{Se} & -2130 \\ \mathrm{CaTe} & -2721 \\ \mathrm{Na}_{2} \mathrm{Te} & -2095 \\ \hline \end{array} $$

Rationalize the following lattice energy values:
$$
\begin{array}{|lc|}
\hline & \text { Lattice Energy } \\
\text { Compound } & (\mathrm{kJ} / \mathrm{mol}) \\
\hline \mathrm{CaSe} & -2862 \\
\mathrm{Na}_{2} \mathrm{Se} & -2130 \\
\mathrm{CaTe} & -2721 \\
\mathrm{Na}_{2} \mathrm{Te} & -2095 \\
\hline
\end{array}
$$

Key Concepts

Effect of Ionic Charge and Stoichiometry

The stoichiometry of an ionic compound, reflected in the number of ions and their respective charges, plays a significant role in lattice energy. Compounds where ions have higher charges will generally have stronger electrostatic attractions and thus higher (more exothermic) lattice energies compared to those with lower charges or a different stoichiometric ratio.

Ionic Radii and Distance Between Ions

The sizes of the ions determine the distance between them in an ionic lattice. Smaller ions can pack closer together, resulting in stronger electrostatic attractions and higher lattice energies, while larger ions increase the distance, reducing the attraction and the lattice energy.

Coulomb's Law

Coulomb’s law explains the electrostatic force between charged particles, establishing that the force (and hence the energy) is directly proportional to the product of the charges and inversely proportional to the distance between them. This principle is key in understanding why compounds with higher charged ions or smaller distances between ions have larger lattice energies.

Lattice Energy

Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It reflects the strength of the forces holding the ions together in the lattice, and is influenced by both the magnitude of the ionic charges and the distances (ionic radii) between the ions.

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