Surface tension | Mendeleev

What happens

Molecules inside a liquid are surrounded by other molecules. At the surface, that environment is asymmetric, so creating more surface requires energy.

The liquid therefore tends to reduce its surface area when other forces allow it. Small free droplets become nearly spherical because a sphere has little surface area for a given volume.

What changes the process

Surface tension also helps explain capillary effects and why some small objects can rest on water without immediately sinking, provided the surface is not broken.

Why it matters

Detergents change the interactions at the interface and usually lower water’s surface tension. That helps water spread and wet surfaces more easily.

Go one step further

A useful way to understand this phenomenon is to separate the driving force from the visible result. Temperature, pressure, concentration, surface area and the nature of the materials can each change the rate or the final state. In real systems, several of these factors often act at the same time.

That is why the same phenomenon can look different in a laboratory, in the kitchen or outdoors. The underlying chemistry or physics stays the same, but the conditions change the balance.