Volatility refers to the tendency of a substance to vaporize or evaporate at a given temperature.

Ionic compounds are held together by strong electrostatic forces between oppositely charged ions. These forces are very strong and require a significant amount of energy to overcome, resulting in:

* High melting and boiling points: Ionic compounds have high melting and boiling points because a lot of energy is needed to break the strong ionic bonds.

* Low volatility: Due to the strong interionic forces, ionic compounds have low volatility. They tend to remain in the solid state at room temperature and do not readily evaporate.

Covalent compounds are held together by weaker covalent bonds, which involve the sharing of electrons between atoms. These bonds are generally weaker than ionic bonds, leading to:

* Lower melting and boiling points: Covalent compounds have lower melting and boiling points compared to ionic compounds.

* Higher volatility: The weaker bonds in covalent compounds allow them to vaporize more easily. This results in a higher volatility.

Examples:

* Ionic compound: Sodium chloride (NaCl) has a high melting point (801 °C) and is non-volatile at room temperature.

* Covalent compound: Water (H2O) has a relatively low boiling point (100 °C) and is relatively volatile.

Exceptions:

There are some exceptions to this general rule. For example, some ionic compounds, such as mercury(I) chloride (Hg2Cl2), can be volatile at elevated temperatures.

In summary:

Ionic compounds generally have low volatility due to the strong electrostatic forces holding them together. Covalent compounds typically have higher volatility due to the weaker covalent bonds between atoms.