Properties of Water

Properties of Water

Polarity:

Water is formed by a polar covalent bond which means that water is a polar molecule. This means that electrons are not shared eqaully throughout the molecule which produces slight negative and positive charges. When the negative end of the water molecule attracts the positive end of another water molecule, this creates a hydrogen bond. A hydrogen bond is a bond between two polar molecules. The hydrogen bonds that form between water molecules cause some of the other essential, and unique, properties of water.

Adhesion/Cohesion:

Adhesion, or capillary action, is when water molecules are attracted to other substances with a negative or positive charges. This is why water "climbs" up a piece of paper or a straw above the surface level of the water.                     This figure shows water adhesion >

When the negative end of a water molecule attracts the positive end of another water molecule, and the molecules stick together, this is called cohesion.

If the water molecules are more strongly attracted to each other than to the surrounding material, they bead up and try to get as close to each other as possible. If there is a stronger attraction to some other material, they spread out and try to get close to the other material.

Surface Tension:

Surface tension is caused by cohesion when the water molecules bunch together. As the molecules get closer to each other, it creates tightness across the water's surfaces.

The reson why this paperclip isn't breaking the surface is because it doesn't have the weight to break the hydrogen bonds that are keeping the molecules together.

Specific Heat:

Specific heat is the heat needed to raise a substance's temperature by 1 degree Celcius. Water is special because it has such a high specific heat. The reason why the specific heat is so high is because the attraction between the H2O is so strong that it takes more energy than usual to shake up those molecules to make them hotter.

Universal Solvent:

Water is also unique because it is the universal solvent. Most substances are soluble in water. When a substance is being dissolved, polar water molecules attract the other polar molecules that are being dissolved. However, water cannot dissolve non-polar molecules such as fats or oils because the non-polar molecules do not have a positive and negative charge for the water molecules to attract.

What I expect to learn.

In this years Honors Biology course I look forward to learn about a variety of things. I expect to learn some of the same material as the end of last year, but with more detail. I hope we go more in depth with atoms and molecules and also I expect to learn about diseases, hormones and inheritence, organisms, and evolution. I think that web tools and blogging will help our learning experience because it gives us all opportunities to share information and debate about topics without being in the classroom. It also incoporates the computer, where a lot of us spend a great deal of our time. With the incorporation of a computer, it will encourage us to converse about the different topics in our science class, while enjoying ourselves at the same time.