Mickey Mouse Molecule



Name: Group: Date: Period:

Mickey Mouse Molecule

Background: Water is one of the simplest substances on Earth, and yet it is something that we must have in order to live. A person can survive only about three days without water. Water is so common to us that we often ignore some of its simplest characteristics. Pure water is clear. It has no odor and no taste. These are just three of the properties of water. There are many others that are less obvious. For example, it takes a lot of heat to make water hot, and even more to make it boil.

All of the properties of water can be explained by the way the water molecule is built. In every water molecule 2 Hydrogen atoms are joined to 1 oxygen atom through chemical bonds. The bond between the hydrogen and oxygen happens when the two atoms share 2 electrons between them—one electron from hydrogen and one from oxygen.

In this activity, you will learn how hydrogen and oxygen are joined and also about some characteristics of the bond between them. By understanding these 2 things, you can understand many of the properties of water.

Objective: Construct a model of the water molecule learning/reinforcing the concepts of

polarity and hydrogen bonding.

Materials: 1 paper pattern, scissors, glue, markers/colored pencils (blue & red)

Procedure:

1. Color the hydrogen atoms blue and the oxygen atom red.

2. Using the periodic table & what you know of atomic structure fill in the information for the nuclei of 2 oxygen atoms & 4 hydrogen atoms.

3. Cut out the pieces (atoms, nuclei & electrons) of the water molecule. (DON’T WORRY about cutting the electrons precisely BUT be careful not to lose any of your pieces.)

4. Sketch below the correct Bohr’s diagram for oxygen & hydrogen.

• Oxygen * Hydrogen

5. Using the diagrams as a guide: glue the nuclei & electrons onto their corresponding atoms. You should have 2 complete oxygen atoms & 4 complete hydrogen atoms when you’re finished.

a. Hint: You should have 20 electrons to complete this correctly. Remember to follow the energy rules like your Bohr’s.

6. It wasn’t until the late 1900s that we learned the actual shape of the water molecule. It looks somewhat like Mickey Mouse: with the oxygen being the head and the 2 Hydrogen atoms being the 2 ears. (See his picture above if you’re not familiar or need a refresher ()

7. Now, based on this description glue the hydrogen and oxygen atoms together using a bond bridge for two separate water molecule. The type of bond between hydrogen & oxygen is called a covalent bond because the atoms are sharing their electrons. Be sure when you glue them together you turn the atom to represent the location at which they are sharing.

Because of the way hydrogen and oxygen bond, each hydrogen atom has a slightly positive charge and the oxygen has a slightly negative charge. You probably noticed that the electron from the hydrogen is turned in towards the oxygen molecule. This leaves the nucleus (and it’s positively charged proton) exposed when approached by another atom from the other direction. When an atom approaches the oxygen atom it first encounters its remaining negatively charged electrons in the outermost shell. This is characteristic of & called a polar molecule.

8. Draw a “+” sign & a “-“ sign on the appropriate sides of each of your water molecules.

Because water molecules are polar, they are naturally attracted to each other (“opposites attract”) & tend to stick together. Water molecules stick together by forming a hydrogen bond between the opposite charges. This “sticking together” is one reason why water requires so much heat to warm up and even more to boil. It is also responsible for some of water’s other properties like surface tension, adhesion and cohesion.

9. Use the hydrogen bond bridge & glue your 2 water molecules together. Remember: opposites attract.

Questions:

1. Name the elements found in a water molecule. ______________________________________

2. What is the ratio of the atoms of each element? _______________________

3. A molecule is a combination of atoms which are bonded together. How are the oxygen and hydrogen atoms of water held together? What kind of bond do the share? ________________ _________________________________________________________________________

4. Water is described as being polar. What does than mean?

5. If one object has a positive charge and the other a negative, what will they tend to do to each other? ____________________

6. Using your answer to Question 5, why do you think water molecules tend to “stick” together?

7. How are water molecules held together?

8. Name 3 properties water molecules have due to their polarity:

* * *

Water Pattern Template (enough for 2 water molecules)

Hydrogen

Oxygen

Bonds (Bridges)

Electrons

Nuclei

OXYGEN (double line): HYDROGEN (single line):

-----------------------

____ P+

____ N

____ P+

____ N

____ P+

____ N

____ P+

____ N

____ P+

____ N

____ P+

____ N

Covalent bond

Covalent bond

Covalent bond

Covalent bond

Hydrogen bond

Recall: The molecular formula for water is:

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