Question

Ionic solids do not conduct electricity in the solid state, but are strong conductors in the liquid state and when dissolved in water. Explain.

Short answer

In conclusion, ionic solids do not conduct electricity in the solid state because their ions are locked into fixed positions in a crystal lattice structure, preventing mobility of charged particles. However, when ionic solids are in the liquid state or dissolved in water, the lattice structure breaks down, and the ions become free to move, allowing them to conduct electricity. The mobility of ions in these states enables ionic compounds to be strong electrical conductors in the liquid state and when dissolved in water.

Step-by-step solution

Understand the structure of ionic compounds

Ionic compounds consist of positive and negative ions bonded together in a crystal lattice structure. These ions are held together by the strong electrostatic force of attraction between oppositely charged ions, known as ionic bonds. In a solid-state, the ions are locked into a fixed position, maintaining the crystal lattice structure.

Identify the basic requirements for electrical conductivity

For a substance to conduct electricity, it must allow the flow of charged particles (such as electrons or ions) through its structure. These charged particles must not only be present but also be able to move freely through the substance, creating a current.

Explain ionic compounds in the solid state

As mentioned earlier, in the solid state, ionic compounds have their ions locked in a fixed position within their crystal lattice structure. Although ionic compounds contain both positive and negative ions, these ions are not able to move freely within the solid structure. Due to this lack of mobility of charged particles, ionic solids do not conduct electricity in the solid state.

Explain ionic compounds in the liquid state and when dissolved in water

In the liquid state or when dissolved in water, the rigid crystal lattice structure of the ionic compound breaks down. The heat energy provided when the compound is melted (for liquid state) or through the interaction with water (when dissolved) is sufficient to overcome the electrostatic forces holding the ions in fixed positions. Consequently, the positive and negative ions become free to move, allowing them to conduct electricity. Therefore, ionic compounds are strong electrical conductors in the liquid state and when dissolved in water, as their ions have the required mobility to create a current. In conclusion, ionic solids do not conduct electricity in the solid state due to the lack of mobility of charged particles in the crystal lattice structure. However, when these ionic solids are turned into a liquid state or dissolved in water, the ions gain the requisite mobility and enable the substance to conduct electricity.