Biology Basics for Middle School Students

What About Water?

We all grew up hearing how important water was, but did anyone actually know how important it truly was. Water is around us all the time and it even makes up 70% of your body. Water is not only important to humans, but to plants and animals as well. Water is made from a covalent bond ( the formation of two nonmetals bonding) of hydrogen atoms and oxygen atoms. Knowing what water is made up of helps understand how water is so versatile.

The oxygen atoms in water are bigger than the hydrogen atoms so more substances bond to it. Since opposites attract, hydrogen is positive that bonds with a negative oxygen. Oxygen and hydrogen can bond with other molecules along and similar molecules, which is important in the first property of water that will be discussed.

Since hydrogen is positive it bonds with negative molecules, oxygen is the opposite. Oxygen is bigger than hydrogen so its bonds are stronger. Hydrogen can bond with itself which makes water able to go against gravity- this is called cohesion. Cohesion gives water the ability to have a very strong surface that’s hard to break so some bugs can crawl on it! Cohesion has a property that does the opposite of it- adhesion. Adhesion has water going up against gravity, but adhesion is when water bonds with other molecules.

adhesionCohesion

The next property is specific heat. Water serves as a regulator of temperature for all forms of life. Specific heat is defined as the amount of heat needed to raise the temperature by 1 degree. Water’s high specific heat allows for the sun to be constantly beating on the surface and the heat of water to only increase by about a few degrees. The same applies for at night. This allows the fish and sealife not to get too hot during the warm summer days as well as keeps temperatures low on land.

The next property that is special to water is how it is a universal solvent. Water usually dissolves most solutes it comes in contact with. This is because of how water is structured as a polar molecule. While talking about how water is a solvent, we can talk about molecules that love water and ones that hate water. Water loving molecules are called hydrophilic and molecules that hate water are hydrophobic.

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The last property of water is how dense water is as a solid. Let’s picture a lake in the winter time. Lakes are usually turned into just a sheet of ice essentially, but the aquatic life is still carrying on with life. Well actually water is less dense as solid than compared to itself as a liquid. Water actually has a layer of ice frozen on top of it. Most liquids contract when they are frozen but water doesn’t. Water’s hydrogen bonds are not being broken since molecules can’t move fast enough to break it. This is why water gets ice on top of it.

Handout

Strengthen your understanding of the importance of water and it’s properties by matching the correct pairs from each column. This exercise will show you how much you’ve learned and where are your knowledge gaps about water’s properties.

Pronunciation Key and Vocabulary List

Cohesion-koh-hee-zhuhn Objects sticking to the same objects

Adhesion-ad-hee-zhuhn Objects bonding to other objects

Specific Heat-

Covalent– The sharing of electrons between atoms

Hydrogen– Colorless gas that bonds with oxygen

Oxygen– Gaseous element