Final answer:
The force of attraction between a Ca2+ and an O2- ion is calculated using Coulomb's Law, with the force being proportional to the product of the ionic charges and inversely proportional to the distance squared between them.
Step-by-step explanation:
To calculate the force of attraction between a Ca2+ and an O2- ion, we use Coulomb's Law, which states that the force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. Given the charges of Ca2+ (2) and O2- (-2), we would expect the force to be stronger than between ions with single charges. The formula for electrostatic force is F = k * (q1 * q2) / r2, where k is the Coulomb constant (2.31 × 1016 J pm), q1 and q2 are the charges of the ions, and r is the distance between the ions in picometers.
Thus, for two ions separated by a distance d, the attractive force between two doubly charged ions, like Ca2+ and O2-, would be significantly higher than that of singly charged ions separated by a distance 2d. The ionic charge and the internuclear distance play a crucial role in determining the lattice energy of ionic compounds.