What are the characteristics of ionic compounds?

Ionic compounds are characterised by high melting and boiling points, electrical conductivity when dissolved or molten, and they form crystalline solids.

Ionic compounds are formed when a metal and a non-metal react together. The metal loses electrons to form a positively charged cation and the non-metal gains these electrons to form a negatively charged anion. This transfer of electrons results in the formation of an ionic bond, which is the electrostatic force of attraction between the oppositely charged ions. This strong bond gives ionic compounds their high melting and boiling points as a lot of energy is required to break these bonds.

Ionic compounds also have a unique structure known as a crystal lattice. This is a three-dimensional structure where each ion is surrounded by ions of the opposite charge, resulting in a repeating pattern throughout the compound. This structure contributes to the hardness of ionic compounds and their brittle nature. If a force is applied, the layers of ions can shift, causing ions of the same charge to align and repel each other, leading to the compound breaking or shattering.

Another key characteristic of ionic compounds is their ability to conduct electricity when dissolved in water or in a molten state. This is because the ions are free to move and carry charge. However, in a solid state, the ions are not free to move, so ionic compounds do not conduct electricity in this state.

Lastly, ionic compounds are generally soluble in water. This is because water molecules are polar and can surround the individual ions, pulling them out of the crystal lattice and causing the compound to dissolve. However, not all ionic compounds are soluble, as it depends on the specific ions involved.