In an ionic compound, the relationship between the size and charge of cations and anions plays a crucial role in determining the stability of the compound. The stability of an ionic compound is mainly governed by the electrostatic forces between the positively charged cations and the negatively charged anions. These forces are influenced by the size and charge of the ions involved.1. Charge of the ions: The electrostatic force between the cations and anions is directly proportional to the product of their charges. According to Coulomb's law, the force F between two charged particles is given by:F = k * q1 * q2 / r^2where k is the electrostatic constant, q1 and q2 are the charges of the ions, and r is the distance between their centers. As the charges of the ions increase, the electrostatic force between them also increases, leading to a stronger ionic bond and a more stable compound.2. Size of the ions: The size of the ions also plays a significant role in determining the stability of an ionic compound. As the size of the ions increases, the distance between their centers r also increases. According to Coulomb's law, the electrostatic force between the ions is inversely proportional to the square of the distance between their centers. Therefore, as the size of the ions increases, the electrostatic force between them decreases, leading to a weaker ionic bond and a less stable compound.In summary, the stability of an ionic compound is directly related to the charge of the ions and inversely related to their size. A compound with highly charged and small ions will have stronger electrostatic forces, resulting in a more stable compound. On the other hand, a compound with low charged and large ions will have weaker electrostatic forces, resulting in a less stable compound.