Some of the important properties of ionic compounds are as follows: i. low electrical conductivity as solids and high conductivity in solution or when molten ii. relatively high melting and boiling points iii. brittleness iv. solubility in polar solvents How does the concept of ionic bonding discussed in this chapter account for these properties?

Ionic compounds have low electrical conductivity in their solid form because the ions (both positive and negative) are locked into a crystal lattice structure. This ionic lattice does not allow the ions to move freely and, since electrical conductivity requires the movement of charged particles, ionic compounds are poor conductors in their solid form. However, when in molten form or dissolved in a polar solvent (like water), the ions can move freely, so the electrical conductivity increases significantly.

Ionic bonds are formed due to the electrostatic attraction between positively and negatively charged ions. This strong electrostatic force ensures that these ions are held together tightly and require a considerable amount of energy to break the lattice structure. Thus, ionic compounds have high melting and boiling points because a large amount of energy is needed to overcome the strong ionic bonds that hold the ions together in the crystal lattice structure.

The brittleness of ionic compounds is due to the arrangement of ions in the crystal lattice. When the lattice is subjected to an external force, it may force an ion to shift and become adjacent to another ion with the same charge. This causes a repulsion between the same-charged ions, leading to the breaking of the lattice and resulting in a brittle behavior in ionic compounds.

Ionic compounds are soluble in polar solvents like water due to the electrostatic interaction between the ions in the compound and the polar solvent molecules. The solvent molecules surround the ions, effectively "pulling" them out of the crystal lattice and stabilizing them in the solution. This process is called solvation, and it occurs more readily with polar solvents because their molecular structure allows them to easily surround and stabilize the separated ions in the ionic compound. In conclusion, the concept of ionic bonding accounts for the properties (electrical conductivity, high melting and boiling points, brittleness, and solubility in polar solvents) of ionic compounds by understanding the nature of the strong electrostatic forces between ions, the stability of the crystal lattice structure, and the interactions between ions and polar solvents.