3.2 Properties of Water
Completion requirements
Unit A
Module 1 ~ Lesson 3
Properties of Water
Hydrogen bonding gives water special properties.
A water molecule is made up of two hydrogens and one oxygen molecule. Each water molecule has a slightly positive charge near the hydrogen and a slightly negative charge by the oxygen. This causes water molecules to be strongly attracted to other water molecules. This attraction is so strong, it is called a hydrogen bond, and is what gives water its special properties like cohesion, adhesion and a high specific capacity. It is also what allows ionic compounds and polar compounds to dissolve easily in water, which is why water is often called the universal solvent.
Water has the following special properties. Click on the tab to learn more.
Water is known as the universal solvent
Polarity makes water a good solvent for ionic compounds or polar covalent molecules.
Since water is a polar molecule, the negatively charged oxygen end of the molecule is highly attracted to the positive ion in ionic compounds. This attraction allows the positive and negative ions to be pulled apart and dissolved in water. The same attraction occurs with the negative ion and the positive hydrogen end of the water molecule.
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Cohesion is the attraction of water molecules to other water molecules.
Surface tension is a result of cohesion.
Since water molecules are charged, they are also strongly attracted to each other. This results in water forming droplets easier than other liquids. It is also responsible for the high surface tension of water.
Adhesion is the attraction of water molecules to other charged particles.
Glass is slightly charged. Adhesion is what allows you to fill a glass over the top.
Since some surfaces are slightly charged, water is attracted to them. Adhesion is important in the transport of water from roots to leaves through the xylem.
Water has a high specific heat capacity.
Specific heat capacity is the amount of energy required to raise 1g of a substance by 1 degree Celcius.
Water uses a large amount of energy to be warmed and releases a large amount of energy as it is cooled. This property of water moderates climates, especially those close to a large body of water.
Read
Read "Section 2.1: The Role of Water in Cycles of Matter" on pages 33 to 40 of your textbook. This material was covered in Science 10 and you may already be familiar with it.