Which of the following compounds requires the most energy to convert one mole of the solid into separate ions? (a) \(\mathrm{K}_{2} \mathrm{S}\) (b) \(\mathrm{K}_{2} \mathrm{O}\) (c) CaS (d) \(\mathrm{Cs}_{2} \mathrm{S}\) (e) CaO

Ionic compounds are substances composed of positive and negative ions held together by strong electrostatic forces, known as ionic bonds. These compounds form when atoms of metallic elements give up electrons to atoms of non-metallic elements, creating ions with opposite charges that attract each other.

The structure of ionic compounds is typically a crystalline lattice where each ion is surrounded by ions of the opposite charge. This maximizes the attractive forces and minimizes repulsion between ions with the same charge, leading to the formation of a stable ionic solid.

The energetics of ionic solids relates to the energy changes involved in forming or disrupting the ionic lattice. Lattice energy is a key concept here, defined as the energy required to completely separate one mole of a solid ionic compound into its gaseous ions.

Compounds with higher lattice energies are generally more stable and have higher melting points. To compare lattice energies, we look at the charges of the ions involved and their sizes. A greater charge magnifies the energy, while smaller ions, being closer together, also result in a stronger attraction and thus higher lattice energy.

The charge and size of ions play a pivotal role in the strength of the ionic bond. The charge on an ion affects how strongly it attracts or repels other ions. Ions with higher charges will exert stronger electrostatic forces, requiring more energy to overcome these forces when separating the ions.

Similarly, the ionic radii determine how close the ions can get to each other in the lattice. Smaller ions can pack more tightly together, increasing the overall attraction within the lattice. Therefore, a compound with smaller, highly charged ions will generally have a higher lattice energy than a compound with larger, less charged ions.

Chemical bonds, such as ionic bonds, are the forces that hold atoms or ions together in a compound. Ionic bonds form between atoms with a large difference in electronegativity, typically between metals and non-metals. In these bonds, electrons are transferred from the less electronegative atom to the more electronegative one, resulting in the formation of positive and negative ions.

The strength of the ionic bond is a significant factor in the compound's properties, including its melting point, boiling point, and hardness. It's important to recognize that ionic bonds are just one type of chemical bond. Others include covalent bonds, where electrons are shared between atoms, and metallic bonds, found in pure metal structures.