Water And Oceanography
Water

Water Molecule



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Water
Jose Juan Gutierrez's image for:
"Water Molecule"
Caption: Water
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Image by: Michael Melgar
© CC-BY-SA-3.0 via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Michael_Melgar_LiquidArt_resize_droplet.jpg

Water (H2O) is the most abundant molecule on Earth. Water covers approximately 70% of the Earth´s surface. The oceans contain about 96.5% of all water on the planet and 3.4% is found in lakes, rivers and ice glaciers; the remaining 0.001% is contained in the atmosphere as water vapor. Water moves continually among the Earth in an endless cycle known as the water cycle and is very important to all life forms on Earth. Climate and weather are influenced by the physical properties of water. Water is the only substance known to exist in liquid, gaseous, solid states and many substances can dissolve in it.  The properties of water stem from its ability to affect the electric charge of the atoms of other substances while they're chemically bonded to oxygen.

Water is everywhere

Water is wherever you look around. You can see it in the sky in the form of water vapor. In the atmosphere, water is continually changing from one state to another.  The unique chemical properties of water make it one of the only natural substances that can acquire a number of three different states: liquid, such as water; solid, in the form of ice; and gas, as water vapor. The endless circulation of water on Earth is known as the water cycle. During the water cycle, water undergoes several processes, which makes it change states many times, from a liquid to vapor to solid and then to a liquid again.

Properties of water

Water is unique when compared to other molecules of a similar atomic structure (H2S, NH3), as water can exist in liquid state rather than in gaseous state at the surface of the Earth. Most properties of water stem from its tendency to form strong hydrogen covalent bonds, with a separation of charges between electronegative oxygen and electropositive hydrogen atoms. Separate charges gives water a high dielectric constant allowing it to dissolve a great number of chemical substances.

The ability of other substances and ions to dissolve in water is due to its polarity. Lots more water properties result from water´s hydrogen bonds. For instance, ice floats on a body of water, such as a cube of ice into a glass of water or an iceberg at the poles. This is the result of hydrogen bonds holding water molecules further apart in a solid, making it less dense than in a liquid. Other unique chemical properties of water, including high specific heat, strong surface tension, its ability to dissolve other substances and many more properties of water are due to hydrogen bonding.

Dynamic interactions

The properties of water derive from the shape of its molecule. A water molecule has two hydrogen atoms arranged at an angle of 104.45% from each other. The electrons tend to concentrate in the direction of the oxygen atom and away from the two hydrogen atoms. Strong covalent bonds occur when two atoms share electrons with each other. The unequal attraction of electrons between hydrogen and oxygen atoms causes different electronic charges, with oxygen being partially negative and hydrogen slightly positive. Although weaker than covalent bonds, hydrogen bonds contribute abundantly to the many unique properties of water.

Although water is one of the most common substances on Earth, it is not as ordinary as it may seem. The chemical properties of water make it one of the most complicated of the substances. After decades of studies, scientists still are trying to decipher some of its unknown properties. Oceans supply most of the water that is absorbed by the atmosphere in the form of water vapor and is returned as precipitation. These natural events move water around the world. Plants provide 10% of this water in the atmosphere through transpiration.

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.nsf.gov/news/special_reports/water/index_low.jsp?id=properties
  • InfoBoxCallToAction ActionArrowhttp://ga.water.usgs.gov/edu/watercycletranspiration.html