Surface tension relates to the tendency of liquids to minimize their surface area. We can see the effects of surface tension by floating the paper clip on water. Although the paperclip is denser than water and will sink if it breaks the surface of the water, the surface tension provides enough force to keep it above the surface. To understand the origin of surface tension, we can consider intermolecular forces. Water molecules within the interior of the liquid experience intermolecular forces with other molecules surrounding it in all directions. Water molecules at the surface, however, experience a net force pulling them into the liquid. Surface tension of a liquid is the energy required to increase the surface area by a unit amount. For example, the surface tension of water at room temperature is about 72.8 millijoules per meter squared. Surface tension increases with increasing intermolecular forces. If a liquid like water doesn't have the force of gravity to keep it in a container, the surface tension of the water will cause it to take the shape that minimizes surface area. So in a zero gravity environment, water takes the shape of a sphere. Viscosity is resistance of a liquid to flow. If we compare the viscosity of hydrocarbons of different lengths, we can see that viscosity generally increases with increasing intermolecular forces. Viscosity also decreases with increasing temperature. Capillary action is the ability of a liquid to flow against gravity up a narrow tube. Capillary action is an interplay between cohesive forces and adhesive forces. Cohesive forces are the attraction between molecules in a liquid. Adhesive forces are the attraction between liquid molecules and the surface of the tube. So adhesive forces pull a liquid up along the sides of the tube, and cohesive forces pull the rest of the liquid along.