Why are water molecules attracted to each other? Do you ever wonder why the water flows ever so gently on your skin?
Or, do you know why and how it gets sucked up a straw without doing anything?
And, yes, why on earth do you find ice floating on water and not sinking? Well, that has something to do with the fact that water molecules are attracted to one another.
But, why do they attract each other?
It happens because water is composed of polar molecules, creating a positive and negative charge on hydrogen and oxygen respectively.
Why Are Water Molecules Attracted to Each Other?
Having polar molecules is a key characteristic of water.
Water molecules (H2O) are characterized by the presence of polar covalent connections between their constituent hydrogen and oxygen atoms.
A water molecule has no net charge, but its polarity gives hydrogen a little positive charge and oxygen a slightly negative charge.
And this is the reason why water molecules are attracted to each other.
Understanding the Polarity of Water Molecules
Polar molecules are defined as molecules with regions of both negative and positive charge, and water is an excellent example of this polarity.
Because oxygen is more electronegative than hydrogen, it contributes to the negative charge in water.
Consequently, a shared electron is more likely to be located close to the oxygen nucleus than the hydrogen nucleus.
This partial negative charge is located near the oxygen atom. And this partial positive charge is located near both hydrogen atoms in water because water is a nonlinear molecule.
Because of this charge, water gets the ability to attract other molecules.
Attracting Other Molecules and Ions
Many biomolecules, including nucleic acids, sugars, and certain amino acids, are polar and attracted to, or repelled by water.
Here, you have to understand the concept of hydrophilic and hydrophobic.
- Hydrophilic describes how readily a polar substance interacts with or dissolves in water.
- Hydrophobic refers to how difficult it is for water to react with other substances.
For instance, water interacts poorly with nonpolar molecules, such as fats and oils.
For example, in oil and vinegar salad dressings, the oil and vinegar molecules are separated rather than dissolved in the oil.
Witnessing the Power of Attraction of Water
Water has a strong tendency to adhere to many different surfaces, including the surfaces it naturally forms drops on, such as:
- Organic tissues
Fact: If you soak a paper towel in a glass of water, the liquid will "travel" up the towel, and it will keep climbing the towel until the force of gravity is too great for it to withstand.
The Concept of Hydrogen Bonding and Water Attracting Water
Water molecules make extraordinarily strong connections with each other because they are positively and negatively charged on opposite sides.
Specifically, the positive side of a hydrogen atom is drawn to the negative side of an oxygen atom in an adjacent molecule.
Ultimately, a link forms between them, which we know as hydrogen bonding
Bonding and Evaporation of Water Molecules
We all know water eventually evaporates, but the truth is that it does not evaporate as quickly as you might think.
It takes up to 100C to break apart the molecules because the hydrogen bonds are extremely solid. That is why we do not just have water vapor on Earth, but rather rivers, lakes, oceans, and rain.
Interestingly, water molecules do not necessarily cling only to other water molecules. Polar molecules work more like magnets.
It means that water can dissolve proteins and salts and transport these nutrients to where they are needed in animals, trees, plants, and humans.
The Role of Capillary Action in Water-Attracting Water Molecules
In the same way, water molecules are drawn to other molecules, other surfaces attract them as well.
Therefore, if you have a very narrow tube, you will notice those molecules becoming attracted to the edges.
At the same time, they will be drawn along the tube, sometimes even moving against gravity.
The process through which water moves up a plant’s stem is termed capillary action, which becomes possible because of water molecules attracting each other.
Fact: No electricity can be conducted through pure water, and it begins to act as a conductor once the water begins to dissolve the materials around it.
Understanding More about the Capillary Action
Moving water around requires the capillary action of several different surfaces.
- The forces of cohesion
- The action of adhesion
As you may have already gathered, water molecules like to connect to each other, which is called the force of cohesion. But, you also know that water is sticky, which tells you about its “adhesive” nature.
Both these forces work together to make the capillary action possible. But, there is another element at work here, and that is surface tension.
When water adheres to the sides of a container, it exerts a force upwards at the liquid, causing the meniscus to curve upwards. As a result of surface tension, the surface is kept together.
Understand that capillary action takes place when the bonding forces between liquid molecules are weaker than the adherence to the walls.
The Importance of Capillary Action of Water
The binding abilities of water molecules to initiate the capillary action is important for so many processes in the real world. For instance:
Importance of Binding Power of Water for Plants
Water with its hydrogen bonding helps with capillary action, which in turn helps trees and plants thrive.
Plants are able to absorb water from the ground because of how deep their roots go into the soil. The plant’s roots absorb the water, which also carries the nutrients it needs to grow.
Water is able to reach the roots thanks to capillary action. Capillary action, however, can only “draw” water up a very short distance before it can no longer defy gravity.
But, that is when the cohesive and adhesive forces of water come into play to transport water all the way to the farthest leaf.
Fact: Water comes with an extremely high heat index and can absorb a lot of heat before it eventually becomes hot to the touch.
A Role in the Drainage of Tear Fluid
Do you think it would be impossible for tear fluid to come out of your eye without the capillary action of water?
That action is absolutely essential for the outflow of the constantly produced tear fluid from the eyes.
Tears are secreted into the eye by two microscopic tubes called lacrimal ducts, which can be found in the eyelid.
The Attraction of Water Molecules and Surface Water Tension
It is a no-brainer that it hurts if your hand hits the water’s surface. Almost like a solid object, right?
However, beneath the surface, you will find something rather lovely: soft and fluid. That is so bizarre, and we never even consider it.
It is common knowledge that water molecules gravitate toward other water molecules.
However, surface water molecules are surrounded by air, making them less likely to form hydrogen bonds with their surroundings.
As a result, the bonds they make with the available surrounding water molecules are much stronger.
It means they are closer together, creating a denser surface. This is why landing on your stomach hurts so much.
The Role of Water Attracting Water Molecules in the Floating Ice
Okay, so why do you think the ice floats on water and does not sink? Again, it has something to do with how water molecules interact with each other.
Ice crystals are formed when water molecules join together in a hexagonal pattern during the freezing process. To put it another way: it is why snowflakes are so gorgeous.
These lovely stars form when they expand outward from a central hexagon.
Perhaps you are asking what, if anything, hexagons have to do with being afloat. Well, when a liquid solidifies, the molecules tend to grow closer together, not further away.
It means water molecules take up more space when they are in their ice form.
In other words, the ice may have the same number of molecules but they weigh a lot less as ice as compared to liquid water. And that is the reason why those water molecules keep floating in the form of ice.
Fact: Water is elastic and extremely sticky, which is the reason why it has high surface tension.
Why are water molecules attracted to each other? Well, it is mainly because of their chemical makeup and the way those molecules are placed in a triangle.
In fact, water contains polar molecules with opposing charges, and you already know, “opposites attract each other.”
That is the reason why there is a strong connection between water molecules, known as hydrogen bonds. And these bonds play a big role in making different processes work to keep life going on the planet earth.