Final answer:
The appearance of substances at the atomic level when dissolved in water is determined by the interactions of molecular forces and the principle of 'like dissolves like'. Ionic compounds, when dissolved, dissociate into ions that are surrounded by water molecules, and solubility varies widely among different substances.
Step-by-step explanation:
What determines what something looks like at the atomic level when it dissolves in water? This is chiefly influenced by the interaction of molecular forces. At the atomic level, when substances dissolve, the nature of the solute (the substance being dissolved) and the solvent (water, in this case) plays a crucial role. The principle 'like dissolves like' implies that attractions between solute and solvent particles have to be similar to successfully form a solution. For instance, water being a polar solvent is adept at dissolving ionic compounds and other polar molecules.
When we consider the dissolution of ionic compounds in water, such as table salt (NaCl), the process includes the separation of Na+ and Cl− ions from their crystalline structure. Water molecules attack the ionic compound and create 'spheres of hydration' around each ion due to the ion-dipole interactions. This disruption of ionic bonds leads to the dissociation of the compound into its constituent ions. Moreover, the stable nature of a true solution like sugar water indicates that the solute particles, including ions or molecules, don't settle or separate from the solution even after an indefinite period or passing through a filter.
The solubility of a solute in water refers to the degree to which it can be dissolved, which can vary widely based on the substance's chemical nature. However, predicting the exact solubility is complex, given the diverse behaviours of different ion groups and molecules. When observed under a microscope, dissolved particles may not be discernable as they are typically less than 1 nm in diameter, unlike when a solution may appear clear to the eye.