Water. Part 1/2: Next time you’re drinking water…

Every single person knows that we need water to live. So we drink water on a daily basis. We are  told that drinking more water improves our skin, our hair and our metabolism. So we buy those special bottles that monitor how much water we drink in a day. But do you know why water is good for you? 

The basic building blocks

Water is made up of two elements: hydrogen and oxygen. Two hydrogen atoms covalently bond to one oxygen atom. Covalent bonding means that electrons are shared between the two elements to make them stable. The bonding looks something like this:

Covalent Bonding of Water. Photo Credit: Lumenlearning

That is just one water molecule. The water we see everyday have loads of water molecules in them. These water molecules are also bonded to each other, so they can move together as one body of liquid. They are bonded through hydrogen bonds. Hydrogen bonds are formed because water is a dipolar molecule. Oxygen is slightly negative and hydrogen is slightly positive. Therefore, following the laws of attraction, the positive hydrogen atom from one water molecule will bond to the negative oxygen of another water molecule. 

Photo Credit: BC Campus Open Textbook

That is the boring textbook stuff but understanding that, opens up the intriguing and almost magical properties of water.

Have you noticed that when you drink out of a straw, the water is pulled up in a column of water and not as little drips? This is due to cohesion between water molecules. The water molecules are attracted to each other more than they are attracted to the air so they bind together and form a large column. Although we only use this property to drink out of a straw it helps organisms to live. For example, Pond Skaters can ‘walk on water’ because they are not heavy enough to break the hydrogen bonds in water. 

Plants can draw water up from the roots to the leaves, against gravity!! This is due to adhesion which means that water is able to bind to other substances easily. That is why your hands are wet after you wash them; the water doesn’t just run off. 

A quick and easy experiment to do at home: put cabbage leaves into a glass of water mixed with food colouring. Wait at least a day and you can see the colour in the water go up to the leaves.

Cabbage Experiment. Photo Credit PagingFunMums

Water also acts as a great solvent. Substances can dissolve in water very easily because it is dipolar. The + Hydrogen bonds with the – solute and the – Oxygen bonds with the + solute. Consequently, water acts as a transport medium for glucose, oxygen, carbon dioxide and urea around our bodies or for nitrates and magnesium around plants. 

80% of cytoplasm (where chemical reactions take place in cells) is water and 92% of the blood plasma (which carries dissolved substances) is water. Chemical reactions can take place because of the usefulness of water. Without water our bodies would not work because we wouldn’t be able to respire or sweat or remove toxins in waste products.

Next time you’re drinking water (which is hopefully soon) take a minute to think about why and how water works.

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