When discussing the conductivity of substances when dissolved in water, we typically consider ionic and covalent compounds:
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Ionic Compounds: These compounds are formed from the electrostatic attraction between positively and negatively charged ions. When ionic compounds, such as sodium chloride (NaCl), are dissolved in water, they dissociate into their respective ions (Na⁺ and Cl⁻). The presence of these free-moving ions in solution allows the solution to conduct electricity very well, making ionic compounds highly conductive in water.
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Covalent Compounds: In contrast, most covalent compounds do not dissociate into ions when dissolved in water. Many covalent substances (e.g., sugar) do not produce ions and thus do not significantly conduct electricity in solution. Some covalent compounds can be polar and interact positively with water (like acids), but they still do not dissociate into ions in the same way ionic compounds do.
In summary, ionic compounds are highly conductive when dissolved in water due to the presence of free-moving ions, while most covalent compounds are not conductive because they do not produce ions in solution.