The sensation of wetness associated with water is a result of the unique properties of water and its interaction with our sensory perception.
Adhesion and Cohesion: Water molecules are polar, with a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity results in strong hydrogen bonding between water molecules. The cohesive forces between water molecules cause them to stick together, creating a liquid with high surface tension. Additionally, water molecules can adhere to surfaces, like your skin, due to the attractive forces between water and other substances.
Capillary Action: Water can be drawn into small spaces and move against gravity due to capillary action, which is a result of the combination of cohesive and adhesive forces. This capillary action contributes to the spreading of water on surfaces.
Wetting Agents: Water has the ability to wet surfaces, meaning it can spread across and adhere to surfaces rather than forming droplets. This is influenced by the interactions between water and the molecules of the material it comes into contact with. Substances that reduce surface tension and encourage spreading are often referred to as wetting agents.
Sensory Perception: Our skin contains receptors that can detect the presence of moisture. When water comes into contact with the skin, it interacts with nerve endings, sending signals to the brain that we interpret as the sensation of wetness.
In summary, water is considered wet because it has the ability to adhere to surfaces, spread out due to cohesive and adhesive forces, and interact with our sensory receptors. The wetness sensation is a result of the physical properties of water and its interactions with the environment and our bodies.