We can define average bond enthalpies and bond lengths for ionic bonds, just like we have for covalent bonds. Which ionic bond is predicted to be stronger, Na—Cl or Ca—O?

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

Verified step by step guidance

Step 1: Understand that the strength of an ionic bond is influenced by the charges on the ions and the distance between them, which is related to the bond length.

Step 2: Recall that ionic bonds are stronger when the ions have higher charges. NaCl involves Na⁺ and Cl⁻, while CaO involves Ca²⁺ and O²⁻.

Step 3: Compare the charges: Na⁺ and Cl⁻ each have a charge of ±1, whereas Ca²⁺ and O²⁻ each have a charge of ±2. Higher charges generally lead to stronger ionic bonds.

Step 4: Consider the bond length: Ionic bonds are also stronger when the ions are closer together. Typically, smaller ions form shorter, and thus stronger, bonds.

Step 5: Conclude that Ca—O is predicted to be stronger than Na—Cl due to the higher charges on the ions involved, which outweighs the effect of bond length in this comparison.

Key Concepts

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

Ionic Bonding

Ionic bonding occurs when electrons are transferred from one atom to another, resulting in the formation of charged ions. These oppositely charged ions attract each other, creating a strong electrostatic force that holds them together. The strength of an ionic bond is influenced by the charges of the ions and the distance between them.

Bond Enthalpy

Bond enthalpy, or bond dissociation energy, is the amount of energy required to break a bond in a molecule. It is a measure of bond strength; higher bond enthalpy indicates a stronger bond. For ionic compounds, bond enthalpy can be influenced by the size and charge of the ions involved, with smaller ions and higher charges typically leading to stronger bonds.

Lattice Energy

Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It is a crucial factor in determining the stability and strength of ionic compounds. Lattice energy increases with the charge of the ions and decreases with increasing ionic radius, making it essential for comparing the strength of different ionic bonds, such as Na—Cl and Ca—O.