Why does water stick together

Park Passes. Technical Announcements. Employees in the News. Emergency Management. Survey Manual. Adhesion and cohesion are important water properties that affects how water works everywhere, from plant leaves to your own body.

Just remember Cohesion : Water is attracted to water, and Adhesion : Water is attracted to other substances. I used to wake up in a cold sweat because I could not get the concepts of water adhesion and cohesion clear in my mind. If you have that problem, too, then read on to learn about these important properties of water Cohesion : Water is attracted to water Adhesion : Water is attracted to other substances.

Adhesion and cohesion are water properties that affect every water molecule on Earth and also the interaction of water molecules with molecules of other substances. Essentially, cohesion and adhesion are the "stickiness" that water molecules have for each other and for other substances. A water drop is composed of water molecules that like to stick together-an example of the property of cohesion.

In the picture of pine needles above, the water droplets are stuck to the end of the pine needles-an example of the property of adhesion. Also noticeable in this picture is the effect that gravity has on the water drops.

Gravity is working against both adhesion and cohesion, trying to pull the water drop downward. Adhesion and cohesion are winning the battle so far, as the drops are sticking to the pine needles. If you just look at the picture of the water drop sitting of the leaf, you might think the water drop has a "skin" holding it into a sort of flattened sphere although there is nothing flat about a water drop in outer space. It turns out that this surface tension is the result of the tendency of water molecules to attract one another.

The natural form of a water drop occurs during the "lowest energy state", the state where the atoms in the molecule are using the least amount of energy.

For water, this state happens when a water molecule is surrounded on all sides by other water molecules, which creates a sphere or ball perfectly round if it was in outer space. On Earth, the effect of gravity flattens this ideal sphere into the drop shape we see. Although you may have heard of a "skin" where water meets the air, this is not really an accurate description, as there is nothing other than water in the drop.

What is the shape of a raindrop? Are they really tear-shaped? Maybe not. Find out here. Water is highly cohesive—it is the highest of the non-metallic liquids. Water is sticky and clumps together into drops because of its cohesive properties, but chemistry and electricity are involved at a more detailed level to make this possible. More precisely, the positive and negative charges of the hydrogen and oxygen atoms that make up water molecules makes them attracted to each other.

If you've played with bar magnets you will know that the north pole of one magnet will repel the north pole of another magnet, but it will attract the south pole of another magnet. Opposite magnetic poles attract one another much like positively charged atoms attract negatively charged atoms in water molecules. In a water molecule, the two hydrogen atoms align themselves along one side of the oxygen atom, with the result being that the oxygen side has a partial negative charge and the side with the hydrogen atoms has a partial positive charge.

A gas is a physical state of matter where the molecules are far apart and moving very quickly. But, because of the hydrogen bonds, as water molecules come together they stick to one another for a small, but significant amount of time.

This slows them down, and holds them closer to one another. They become a liquid; a different state of matter where the molecules are closer and slower than in a gas. Molecular water, therefore is a liquid at room temperature, a fact that is profoundly significant for all living things on this planet. Everything dissolves in water. Stone, iron, pots, pans, plates, sugar, salt, and coffee beans all dissolve in water.

Things which dissolve are called solutes and the liquid in which they dissolve is called a solvent. The water molecules surround the charged solute; positive hydrogens close to negative charges and negative oxygens close to positive charges on the solute molecule.

All this interaction suspends the solute molecule in a sea of water molecules; it disperses and dissolves easily. Electrons in the bonds between identical atoms H-H are shared uniformly, so the electrons spend equal amounts of time around each atomic center. These covalent bonds are non-polar. See Fig. A molecule of water has two hydrogen atoms. Both of these atoms can form a hydrogen bond with oxygen atoms of different water molecules.

Every water molecule can be hydrogen bonded with up to three other water molecules See Fig. However, because hydrogen bonds are weaker than covalent bonds, in liquid water they form, break, and reform easily.

Thus, the exact number of hydrogen bonds formed per molecule varies. Molecules of pure substances are attracted to themselves. This sticking together of like substances is called cohesion. Depending on how attracted molecules of the same substance are to one another, the substance will be more or less cohesive. Hydrogen bonds cause water to be exceptionally attracted to each other. Therefore, water is very cohesive. Our experience with water, however usually involves water touching something else or being acted upon by gravity.

In space, water is able to form perfectly round spheres because the attraction of water to itself pulls the water into the shape with the least amount of surface area compared to the volume — a sphere. A European Space Agency astronaut Pedro Duque of Spain watches a water bubble float between him and the camera, showing his image refracted, on the International Space Station.

B A large water sphere made on a 5 cm diameter wire loop by U. Weird Science. Adhesion is similar to cohesion, but it involves unlike i. Water is very adhesive ; it sticks well to a variety of different substances. Water sticks to other things for the same reason it sticks to itself — because it is polar so it is attracted to substances that have charges. Water adheres to many things— it sticks to plants, it sticks to dishes, and it sticks to your eyebrows when you sweat. In each of these cases water adheres to or wets something because of adhesion.

This is why your hair stays wet after you shower. Molecules of water are actually sticking to your hair Fig. Adhesion also explains why soil is able to hold water and form mud.

Investigate the cohesive and adhesive properties of water. The cohesion of water creates surface tension where air and water meet.