why does water have surface tension?
596688
Becaue water is polar and water molecules form hydrogen bonds with each other.
1051142
because water molecules are heavier than air molecules.  If you think about it, these heavy molecules are weighing down (even though they are suspended) on everything around them  with more force (which is proportional to the mass).
899395
What you are seeing is surface tension.  Water molecules have an attraction to each other.  They sort of "hold on" to the water molecules allowing the level to rise without spilling over.  \n\nIf you create the bubble by adding pennies and add a drop of dish detergent you will see that the soap breaks that surface tension and the water will spill.
1067427
Hydrogen bonding of Water molecules: Due to the polar covalent bonds that hold a water molecule together, Hydrogen bonds form where the negative Oxygens and the positive Hydrogens are located.\nThe results of these bonds are as follows:\n \n1. Cohesion: is the sticking together of similar molecules. Water is very cohesive. This allows water to be pulled along a pathway with relative ease.\n \n2. Surface Tension: cohesion allows water to pull together and form droplets or form an interface between it and other surfaces. The measure of how hard it is to break this interface is its surface tension.\nWater allows materials to rest upon it if the surface tension is not broken. Pollen, dust, water insects, and other biological materials are able to remain on the surface of the water because of this tension.\n3. Adhesion: The sticking of one substance to another. Water is a good adhesive. It will cling on to many objects and act as a glue. Capillary Action is an example of cohesion and adhesion working together to move water up a thin tube.\n\n4. Imbibition: The process of soaking into a hydrophilic substance. Water being taken into a sponge, into a seed, into paper towels.\n\n \n5. High Specific Heat: Specific heat of a substance is the heat needed (gained or lost) to change the temperature of 1g. of a substance 1degree Celsius. Heat is the total quantity of kinetic energy due to molecular motion. Temperature measures the intensity of the average kinetic energy of the molecules.Heat and temperature are not the same thing. A Kilocalorie or large C equals 1,000 small calories.It takes 1,000 calories to raise 1,000g. of water 1 degree C. Nutritional Packaging has the calorie measurements in Kilocalories. One gram of Protein = 3 calories. This means 3,000 small calories or 3 Kilocalories.\nThis high specific heat allows water to act as a heat sink. Water will retain its temperature after absorbing large amounts of heat, and retain its temperature after losing equally large amounts of heat. The reason for this is that Hydrogen bonds must absorb heat to break. They must release heat when they form.The Ocean acts as a tremendous heat sink to moderate the earth's temperature.\n \n6. High Heat of Vaporization: Water must absorb a certain amount of additional heat to change from a liquid into a gas. This extra heat is called heat of vaporization. In humans, this value is 576 cal/g. This results in evaporative cooling of the surface. Alcohol has a value of 237cal/g. and chloroform 59cal/g.\nAs one can see water removes much more heat from a surface upon evaporation than does either alcohol or chloroform.\n \n7. Freezing and Expansion of Water: Water is most dense at 4 degrees C. At ) degrees C. it is 10% less dense. Ice floats because maximum Hydrogen bonding occurs at 0 degrees C.\n \n8. Versatile Solvent: Water is a major solvent in nature. When water and another substance is mixed the resulting solution is called an aqueous solution. Any solution contains the following parts:\nSolute( what's being dissolved) + Solvent ( what is doing the dissolving) = Solution.\nSolute Concentration: The concentration of the dissolved materials in relation to the solvent. This is always measured in moles. A mole is the amount of a substance whose mass is in grams is\nnumerically equivalent to the molecular weight in daltons. One must first find the atomic weights of the substance involved and add them together for the representative molecule and change the value to grams.\nMolarity occurs when the mole (gram atomic weight of the substance) is placed in a container and dissolved in one Liter of water.
433818
Water provides more force than air because it is\ndenser and thus has more mass:\n\nF = ma \n\nd = m / volume
961464
i think it's because in solid states, the electrostatic forces keep the positive and negative ions together.  but when placed in water, the ions separate, free to move about in the water.
232794
gravity pulls water down and adhesion and cohesion hold water up. While gravity is a greater force, it helps to maintain a balance of water leaving the stomata.
620099
A bubble is a liquid with AIR inside. Liquid has SURFACE tension, which is EQUAL on all sides of the bubble, therefore it forces itself into a spherical shape.
205650
if you pour it carefully, it should stick together.  Water has a great degree of chemical cohesion, but it's not strong enough to keep the blob together if it has a lot of internal momenti.  If the blob comes out with some varying momentum vectors (if one part of the blob is moving one way and another moving another way), then it will break apart into a few blobs.  If you use a standard water bottle with a thin neck, odds are it's going to come out in a few chunks as the water comes out and the air alternately comes in to fill the space (glug glug glug)\n\nAnd to correct one of the answers, water is not attracted to itself due to its own mass.  Neutral mass only has attractive forces at very large scales (gravity).  Water cohesion and surface tension has to do with the polar nature of the water molecule.  Water molecules are bent with a positive and negative end that form, and while the positive and negative attractions more or less cancel out in the middle of a mass of water, at the surface the bonding is stronger because the molecules are essentially fighting to get back in the middle.  At the surface, there are fewer directions that a water molecule can orient itself without causing unchecked electromagnetic charges (which nature abhors), so they have to orient themselves in a structured 2-dimensional manner at the surface so that each positive end is facing towards the negative end of another water molecule.  This high degree of structure at the surface creates what we know of as surface tension.  It's the force that keeps beads of water on the windshield from spreading out.  It's relatively strong, but for a large mass of water like what would come out of a bottle, the internal momentum of different sections of the blob would far outweigh the forces of cohesion and surface tension.\n\nPicture a big wobbly amoeba, except if an arm stretches out too far, it breaks off into another little blob.\n\nBut if you managed to pour it out REALLY carefully, or if you injected small drops into the air with a syringe, you would get spheres, because there wouldn't be ebough mass of water for any internal momentum to override the surface tension.  And the surface tension would, in fact, make water assume a spherical shape in zero-gravity.
746283
Capillary forces and water potential.  The water potential is the tendency of water to move from one place to another, due to evaporation or stuff dissolved in the water.
20125
All liquids have surface tension, which causes them to stay together (the reason behind bubbles and the reason behind bulged drops). Surface tension is caused by cohesion - attraction between like molecules. When in contact with a surface, water mollecules stick to the surface due to adhesive forces - forces between unlike mollecules. The result is than when a liquid starts to evaporate the outer rim tries to remain attached to the surface. The liquid that is lost in the rim due to evaporation is replensihed by outward flow of liquid from the inner side. The liquid carries solids along with it. When the liuid has fully evaporated it leaves the soilds behind forming the ring.
253045
Water often contains a great deal of suspended air - but it is not visable as they are very small.  When you shake the water, the little bubbles start bumping into each other, and if they are big enough, you will see them.  If they are big enough to see, they will float to the top and pop!\n\nIf you have an aerator on your kitchen sink you can get lots of bubbles from shaking water.  Water that has sat in a bottle undisturbed for a while has most of its bubbles gone.
418087
This is very similar to the floating of a (slightly oily) needle on the water. Surface tension acts like a stretched elastic membrane. The water is always trying to minimize its free surface area (that is, surface that is not contacting and wetting some solid).\nWhen you put an unwettable object on the water it stretches the surface which increases the surface tension. This tension holds up the needle. When you push a tube with an unwettable inner surface into the water, the surface tension tries to minimize the unwetted surface area by not rising into the tube. It will reach a level in the tube that balances the bouyancy due to the immersed air with the surface tension.
676716
The sphere has the smallest surface area among all surfaces enclosing a given volume and it encloses the largest volume among all closed surfaces with a given surface area. For this reason, the sphere appears in nature: for instance bubbles and small water drops are roughly spherical, because the surface tension minimizes surface area.\n\nA sphere surface can also be defined as a surface formed by rotating a circle about its diameter.
975553
Waves are formed by putting directional kinetic energy into water and the surface tension of a liquid acts like a jump rope when you whip it really fast.
913933
Because of the covalent bonds between water molecules. Because water's polar, the molecules are very attracted to each other. It's important because it allows for things such as capillary action, which can be seen in plants absorbing water through their roots and having the water "climb" up the plant against the force of gravity.
947544
It sounds like you're talking about water dripping (rather than flowing) out of a faucet.  \n\nEach droplet will continue to grow in size until its potential energy due to gravity equals (or rather, just barely exceeds) the total surface energy (surface "tension", as we often call it) of the spherical surface that would exist if the droplet were in free space at that instant.\n\nSince the volume (and thus the mass, and thus the potential energy) of each spherical droplet increases as a function of its radius cubed, whereas its surface area (and thus its total surface energy) increases as a function of its radius squared, the above event is inevitable.  And since gravity and the density of water are essentially constant, the critical size of each droplet is likewise.\n\nWant bigger drip-droplets?  Go to the moon, where gravity is weaker.  \n\nI hope I answered the question you were actually asking. :P\n\nEDIT :: And by the way, the connection between my answer and the one immediately prior to mine is that the water droplet's surface energy is governed by the strength of the dipole bonds between its molecules.