Describe the structure of the water molecule and indicate how this structure is responsible for many of the unique properties of this vital compound.
http://www.lsbu.ac.uk/water/
On a more advanced level is the next site.
http://www.lsbu.ac.uk/water/molecule.html
The structure of a water molecule consists of two hydrogen atoms bonded to a central oxygen atom. The oxygen atom is located at the center, forming a bent or V-like shape. Each hydrogen atom shares one of its electrons with the oxygen atom, creating two covalent bonds. The oxygen atom has a slightly negative charge, while the hydrogen atoms have a slightly positive charge. This unequal sharing of electrons creates a polar molecule, meaning that the charges are not evenly distributed.
The unique properties of water are a direct result of its molecular structure. Here are a few examples:
1. Solvent properties: Due to its polarity, water can dissolve a wide variety of substances. The slightly positive hydrogen atoms can attract and surround negatively charged ions, while the slightly negative oxygen atom can attract and surround positively charged ions. This ability to dissolve a wide variety of solutes makes water an excellent solvent for biological processes.
2. High specific heat capacity: Water has a high specific heat capacity, which means it requires a significant amount of energy to change its temperature. This property allows water to act as a temperature regulator, helping to stabilize the temperature of living organisms and their environments.
3. Cohesion and surface tension: Water molecules have a strong attraction to each other, known as cohesion. This cohesive property allows water to form hydrogen bonds with neighboring water molecules. The collective effect of these hydrogen bonds leads to high surface tension, meaning that water forms a "skin" on its surface. This property is responsible for capillary action, where water can move against gravity in plants and small tubes.
4. High heat of vaporization: The hydrogen bonding between water molecules gives water a high heat of vaporization. It requires a significant amount of heat input to break these hydrogen bonds and convert water from a liquid to a gas (vapor). This property is important in the regulation of body temperature through sweating.
In summary, the bent shape and polarity of the water molecule influence its unique properties, such as its ability to dissolve solutes, regulate temperature, exhibit cohesion and surface tension, and have a high heat of vaporization.