Water Cycle - Water (3)
Post Lab 

  • Exploring why water is important.
  • Investigating a water molecule.
  • bond
  • covalent
  • hydrogen
  • ionic
  • oxygen
  • water
  • worksheet
  • hydrogen and oxygen cut outs from lab 

Students learn about angles in a circle.


Water is very important to our everyday lives because of the manner in which hydrogen and oxygen "hold" hands.  The water molecule is very strong, but the way it is arranged, allows many other substances that can "hide" between the hydrogen and oxygen.  What makes water so important?  Water is a peculiar substance with properties that make it an ideal fluid.  If you theoretically calculate the boiling and freezing temperatures of water you will find that water has an unusually low freezing point and high boiling point compared to other molecules that have similar structures (sulfur, selenium, and   tellurium).

How can you explain such a big difference?  The molecular structure of water resembles that of Mickey Mouse's or a teddy bear's head (figure above).  The hydrogen and the oxygen have a very tight covalent bond, where the hydrogen and the oxygen share electrons as they dance and twirl around in the molecule.  The individual molecules of water are also held together very tightly by what  is specifically  called a hydrogen bond.  A hydrogen bond is much stronger than other bonds that molecules have.  Ionic bond is one of those weaker bonds, and substances like salt can be easily be broken up.  Water is a package of power that is hard to break, and it is this strength that allows other substances to dissolve or break up in water, hence the name, universal solvent.

  1. If students are not familiar with using a protractor go over how to determine angles with the paper protractor.  You may want them to cut them out and show them how to measure.
  2. Use the circle on the worksheet to figure out the different angles depending on how much practice they may need.
  3. Instruct the students to use two of the hydrogen and one oxygen to make a representative model of how the elements are bonded.  The two hydrogen’s are 105º between each other as in the diagram in the background information.

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