Chemistry
Charge Density and Ion Hydration in Aqueous Solutions
Quick fact
A single lithium ion, with its high charge density, can attract and hold up to four water molecules in its immediate vicinity, forming a tightly bound hydration shell. In contrast, a larger cesium ion, with the same charge but lower charge density, holds water molecules much more loosely, making it a 'water-structure breaker.'
Why this is interesting
Have you ever noticed that table salt (NaCl) dissolves easily, but adding an egg to salted water makes it float? The secret lies not just in the salt, but in how its ions interact with water molecules. Why do some ions cling to water more tightly than others?