Final answer:
When clay forms colloidal particles in water, they become electrically charged due to an imbalance of ions. Like charges repel, keeping the particles dispersed. This phenomenon is crucial in understanding the formation of land at river mouths.
Step-by-step explanation:
When clay is dispersed in water, it forms colloidal particles which become electrically charged. This charge on the clay particles is typically due to an imbalance of ions within the particles themselves. For example, a colloidal particle of iron(III) hydroxide bears a positive charge due to the excess of positive charges from the iron(III) ions. Similarly, depending on their composition, clay particles can also have an electric charge, which keeps them dispersed and prevents them from settling quickly.
In a colloidal system, like charged colloidal particles repel each other, which prevents aggregation and helps maintain a stable dispersion. Aggregation can occur when these charges are neutralized by ions with the opposite charge, leading to precipitation, which is a key concept in the formation of land at the mouths of large rivers.