The areas where gases and liquids, gases and solids, liquids and solids, or two immiscible liquids meet.
They are only bonded to neighbors beside or below them.
Molecules at the surface are attracted to neighbors next to and below them resulting in a flexible skin.
It contains both polar and nonpolar portions in its structure and thus can be attracted to both the soil and the water.
It must form reasonably strong bonds to other materials but should not strongly bond to itself. It should not degrade while sitting on the store shelf.
Old bonds are broken and new bonds are formed.
More product may be produced in the same amount of time. Materials once thought to be waste products may be turned into marketable materials.
The more surface exposed the greater the chance that reaction will occur.
They have ``holes'' which select or screen molecules that are allowed to pass through and later react.