The Molecular Reason Water Feels 'Wet'
Water feels 'wet' because its molecules have a strong attraction to the molecules of other materials, a property known as adhesion. When water comes into contact with a surface, like your skin, the adhesive forces cause it to spread out and stick to that surface, creating the sensation we perceive as wetness.
Section 2: The Key Forces of Cohesion and Adhesion
Two primary forces are at play: cohesion and adhesion. Cohesion is the attraction between water molecules themselves, which is why water droplets can form beads. Adhesion is the attraction between water molecules and molecules of a different substance. For water to effectively wet a surface, the adhesive forces between the water and the surface must be stronger than water's cohesive forces.
Section 3: A Practical Example with Wax Paper
Consider a drop of water on wax paper. The water forms a distinct bead instead of spreading out. This occurs because the cohesive forces (water sticking to itself) are much stronger than the weak adhesive forces between the polar water molecules and the nonpolar wax surface. In this case, the water does not effectively 'wet' the wax paper.
Section 4: Why Wetness Is Important
The properties that make water feel wet are fundamental to life. The combination of adhesion and cohesion enables capillary action, which allows water to travel up the stems of plants against gravity. This same stickiness also makes water an excellent solvent, capable of dissolving substances and transporting nutrients within our bodies.