By: Shaina Grover
Water is one of the most common resources on the planet; in fact, 71% of the Earth is comprised of water! In addition to this, water is essential to human survival. Our bodies can last only three days without it. However, while we are all familiar with water, not as many people are aware of its properties.
There are several basic properties of water that we can easily identify without much scientific knowledge. For starters, pure water has no color, no taste, and no odor either. The next most obvious property of water is that it is a liquid.
However, water is more than just a liquid; let’s take a closer look at some of the chemistry behind water. The chemical formula for water is H2O, which means that each molecule of water is composed of two hydrogen atoms and one oxygen atom. Water molecules are composed in this manner due to the number of electrons that oxygen and hydrogen atoms have. In any atom, the electrons are organized in shells, with the first level containing a maximum of two electrons and the following ones containing a maximum of eight electrons.
An oxygen atom has eight electrons total. Therefore, the first shell (level) is full, but the second shell only has six. These electrons on the outer shell are referred to as valence electrons. When atoms bond, they look to have a full shell of valence electrons. In this case, the oxygen atom needs two more electrons for a complete shell. Hydrogen atoms have one electron each, meaning that it needs one more electron to have a full valence shell, which is why the oxygen atom needs two of them.
Hydrogen bonding is a term used to describe the attraction between a hydrogen atom (that is bonded to an electronegative atom) and another electronegative atom. In regards to water, it refers to the attraction between a hydrogen atom and an oxygen atom from a different water molecule. Hydrogen bonds are much weaker than the covalent bonds holding together the H2O molecule, and they constantly break and reform when water is in a liquid state. The molecules are a lot closer together because they are unable to move around much. On the other hand, when water freezes and becomes ice, the maximum number of hydrogen bonds are formed, so the molecules are a lot more spread out. When a substance’s molecules are far apart, the substance’s density is lower. Density is the measure of an object’s compactness. Usually, when a substance’s temperature decreases, the density increases because the molecules move less and move closer together. The exact opposite happens with water as the density of ice is less than the density of water. This is why ice floats in water!
Other important traits of water include adhesion and cohesion. Adhesion is the attraction between two different types of molecules, and cohesion is the attraction between molecules of the same kind. An example of water’s adhesive qualities is that it tends to curve up at the ends when placed in a container.
It’s quite interesting that something that appears as simple as water actually possesses many unique and complex characteristics. It’s like the old saying goes: there’s always more than what meets the eye.
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Questions:
1. What is electronegativity?
Electronegativity is defined as an atom’s ability to attract electrons. Atoms with a high electronegativity attract electrons strongly. The greater the distance between the protons and the electrons of an atom, the less electronegative the atom is. Fluorine is the most electronegative element and Francium is the least electronegativity.
2. Why do we need to drink water?
Water is used by the human body for a variety of tasks. For instance, water is responsible for regulating the human body’s temperature as well as creating sweat. Water is also needed in order to digest and break down food. And, of course, drinking water is necessary to prevent dehydration.