What Is Water Polarity

Alexis Jones
4/20/16
Chemistry- Water Polarity
Mrs. Jenny

Polarity: The intermolecular forces between the slightly positively- charged end of one molecule to the negative end of another of the same molecule.
Polarity simply means that the molecule has both a negatively and positively charged end. The polarity of water is important because it is responsible for dissolving other polar molecules like ionic compounds (such as salt) and sugars. To form ions, ionic compounds must be dissolved in water. This is important because for most biological reactions to occur, the reactants must be dissolved in water. Substances that cannot be dissolved by water (such as oils) are called fat soluble and are nonpolar.
Water is composed of polar molecules, and
this is one of it’s most important properties. The word ‘Polar’ means that there is an uneven distribution of electron density. Water is also a bent molecule, it is not linear or straight. Since water is a nonlinear, or bent, molecule, the difference in electronegativities between hydrogen and oxygen atoms generates the partial positive charge near both of the hydrogen atoms and partial negative charge near the oxygen atom.
The atoms within a water molecule consist of two hydrogen atoms and one oxygen atom (H2O), when combined they form a polar covalent bond.
There is no net charge to a water molecule but, since the polarity of water creates a slightly negative charge on oxygen and a slightly positive charge on hydrogen (contributing to water’s properties of attraction); The charges of water are generated because oxygen is more electron loving, or electronegative, than hydrogen. So, it would be more likely that a shared electron would be found near the oxygen nucleus rather than the hydrogen nucleus. When water molecules align with each other, a weak bond is established between the positively charged hydrogen atoms of a water molecule and the negatively charged oxygen atom of a neighboring water molecule; this is known as hydrogen bonding. Hydrogen bonding is actually very important and is also common is living organisms; hydrogen bonding makes water molecules stick to each other, and this cohesion helps pull water upward in the microscopic vessels of plants. Hydrogen bonds also form between bases of DNA to help hold the DNA chain together. Hydrogen bonds give water molecules two additional characteristics as well; surface tension and
cohesion.
Because of the extensive hydrogen bonding in water, the molecules tend to stick to each other in a regular pattern. This phenomenon, called cohesion, is easily observed as you carefully overfill a glass with water and observe the water molecules holding together above the rim until gravity overtakes the hydrogen bonding and the water molecules spill down the side of the glass. Likewise, the cohesive property of water allows tall trees to bring water to their highest leaves from sources below ground.
A special type of cohesion is called surface tension. The tension on the surface of water occurs when water molecules on the outside of the system align and are held together by hydrogen bonding to create an effect similar to a net made of atoms. For example, the surface tension of water allows water spiders to literally walk on water. In conclusion, The polarity of water is very important for more than a few reasons, but hydrogen bonding is more of a foundation of life, thus making it more important. If it wasn’t for hydrogen bonding our DNA wouldn’t stick together and we’d die.