Biology as Ocr Importance of Water Essay

810 WordsAug 28, 20134 Pages
Water is an essential part of sustaining the planet, its ecosystem and humans. We would have not even existed without water as 60% of our bodies are made up of it. Water is a small molecule consisting of two hydrogen atoms and one oxygen atom, which makes up its compound symbol H20. They are covalently bonded together but the shared evenly as the oxygen atom is capable of pulling the shared electrons towards itself (oxygen has more electronegativity than hydrogen), away from the hydrogen atoms which means water molecules become slightly negatively charged at on end and positively charged at the other, making it a 'polar molecule'. Other water molecules are attracted and become bonded to one another due to the molecule's polarity; so the positive charge of the oxygen atom becomes attracted to the negative charge of another hydrogen atom, so a bond forms between, which is the start of a chain reaction of hydrogen bonding of water molecules. When water is in different states, the molecules and hydrogen bonds behave differently. For example, when water is in its liquid state, the molecules form hydrogen bonds with each other and then break them continuously, which gives the water its liquid properties and makes it harder for the water molecules to become gas without having to be boiled first at 100ºC (more specifically 99.98ºC), so a lot of energy has to be put into it to get it to change it's properties to boiling or freezing. On the other end of the temperature scale, for the property of water as a solid it has to decrease in temperature to 0ºC; it's freezing point. At this point, the molecules move less due to the decreased surface area (there was more surface area when the water was in it's liquid and gaseous states) and reduced kinetic energy. More hydrogen bonds form but do not break as easily as they form a semi-crystalline structure which makes ice

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