A molecule is polar when there is an uneven distribution of the charges. This is similar to a magnet in which its opposite ends have different poles (a north and a south pole).

An example of a polar molecule is a water molecule in which one end is slightly positive while the other end is slightly negative.

Recall that a solvent is a substance which dissolves a solute. An example would be a saline solution in which sodium chloride (the solute) is dissolved in water (the solvent).

Water is a good solvent because of an important property: its polarity. Because water is a polar molecule, it can dissolve ionic compounds and various polar molecules. Substances can include sugars, salts, and solvents (e.g. alcohol).

Buffer is a solution of an acid or a base which in reaction with intense acid or base doesn’t allow sudden changes in pH. It is significant in maintaining of constant pH either in chemical reactions outside (experiments) or inside the body (keeping of homeostasis).

Let’s take for example next mixtures: lemonade (squeezed lemon juice), tea, coca cola, sweetened water, and coffee. Lemonade is a suspension because it contains different sizes of lemon pulp particles that cannot be dissolved mostly because of its membrane. Tea can be a solution and suspension too. Tea as a solution when you put tea bag in cup with warm water and after few minutes dispose it, just mix with the spoon to even concentration of tea with water. Also, tea can be a suspension when you make it with home-made dried plants or fruits. Their tiny particles will stay in cup when you dispose large ones. Coca cola is popular soda which is a solution of few compounds and water which are evenly distributed through liquid. Sweetened water can be a solution if you put cub of sugar in warm water and wait until it dissolves completely. Buy, if you put teaspoon of sugar into cold water and just mix it a little bit and drink, sugar won’t dissolve completely so then it’ll be a suspension. Coffee can be also a solution or suspension. It depends on how it’s made and which type of coffee is used.

The water molecule, apparently simple is somehow complex and very special. It consists of two hydrogen atoms and one oxygen atom. Thanks to 8 protons in oxygen’s nucleus, its bond with hydrogen atoms is stronger that among hydrogen atoms which have one each. As a result, the water molecule has partial negative and partial positive charge. Therefore it is a polar molecule. Because of its polarity, water molecules can attract with each other. Type of attraction, between the molecules of the same substance is called cohesion. One molecule of water can connect with four hydrogen bonds at the same time which makes it very cohesive. Cohesion enables linking of water molecules. (connecting of water drops on smooth surface).

Living beings depend on water because their body is made upon it for large 60%. Therefore, every reaction in their organism affects outer conditions and amount of water that is available in their surroundings. Seemingly so simple, water is apparently complex and very valuable. It is liquid from 0 to 100 degrees of Celsius. Thanks to this wide interval and high heat capacity, immediate temperature changes are prevented. Water is also a solvent for most chemicals. Life under the ice is possible thanks to increasing of its volume and making 4 bonds unlike 3.4 of water.