UNIT 2: The Chemistry of Life Biology I Daysheet 17: Atoms, Bonding, Water & pH Name: _______________________________ Date: ____________________

BRAINSTORM : Why is water important for living things?

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Today’s Objective: I can analyze the relationship between water’s structure and its function in living systems Homework: HW17 is due tomorrow!

 

Activity 1: Cornell Notes

 

 

 

• Label the parts of the atom below:

STOP-AND JOT:

What is the charge on a proton ___________________?

What is the charge on a neutron _____________________?

What is the charge on an electron ____________________?

• The glue that holds atoms together is _____________________

• There are two types of chemical bonds:

o _____________ bonds = chemical bonds formed by sharing electrons

o _____________ bonds = force of attraction between oppositely charged

ions

• Label the pictures below as covalent or ionic:

     

• Draw a picture of a water molecule in the space below:

Biology Objective:

   

 

 

 

STOP-AND-JOT:

How do atoms form bonds? ___________________________________

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• Draw a picture of a water molecule in the space below:

• Water has _______________________ = the electrons are not shared equally

between the oxygen and the hydrogens! Oxygen hogs the electrons!

STOP-AND-JOT:

Go back to the picture of the water molecule above. Label the charges on the

picture of your water molecule above.

• ______________________ = water molecules stick to each other

• _______________________ = water molecules stick to other substances

• _______________________ = water is really good at dissolving stuff!

• Water is _______ dense as a solid than liquid = ice floats on water!

STOP-AND-JOT:

Pick a property of water from the list above. Why is this property

important to living things?

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Essential Questions Notes:

 

 

 

 

______Water molecules stick to each other A. Universal Solvent on the surface of a pond, making a surface that bugs can walk on ______ Water in our blood can dissolve and B. Adhesion carry nutrients throughout our body ______ Icebergs floating in the Arctic Ocean C. Less dense as a solid than a liquid provide a habitat for polar bears ______ Water sticks to plant stems, helping D. Cohesion water move up a plant

Summary: Match the properties of water on the LEFT with an example on the RIGHT

ructure of a water molecule by filling in the blanks below!

• Label the pH scale below with the following words: acidic, basic,

neutral

• Give an example of an acid: ______________________

• Give an example of a base: ______________________

• Give an example of a neutral substance: _____________________

STOP-AND-JOT:

What is the only substance with a neutral pH? ______________________

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Activity 2: Introduction to Biochemistry and Water Purpose: To understand the structure of a water molecule Task: As you read the paragraphs below, highlight information that relates to the question on the left Outcome: Answer the questions and create your own water molecule model!

A molecule is made when different atoms create chemical bonds.

The way atoms create these bonds is by sharing their electrons. In a water molecule, one oxygen and two hydrogen bond together by sharing their electrons. However, they do not share the electrons equally. Oxygen hogs the electrons!

Remember, electrons have a negative charge. So when oxygen hogs

the electrons it gets a slight negative charge. And when the hydrogen loses some of its electrons, it gets a slight positive charge. Because water has slight positive and negative charges we say that it is polar.

Because water molecules are polar (they have slight positive and

negative charges), water molecules are "sticky." When you put two water molecules together, the negative oxygen and positive hydrogen are attracted to each other and stick together. Water's "stickiness" makes it able to do lots of cool things in nature that are really important to living things! For example, water molecules on the surface on ponds stick together so well, some insects can walk on them!

1.  How  do  atoms  bond  together  to  form  molecules?  

 

 

 

 

 

 3.  What  do  we  mean  when  we  say  water  is  polar?  

 

 

3.  Why  are  water  molecules  sticky?  

 

 

Oxygen  Hydrogen  

Electrons  

-­‐   -­‐  

Stop  hogging  all  the  electrons!  

I  do  what  I  want!  

Activity 3: Creating a Water Molecule

Stop-and-Jot:

1. Label the oxygen and hydrogen atoms

2. Label the atom(s) that have positive charge with +

3. Label the atom(s) that have a negative charge with and negative charges

Procedure to create your water molecule:

1. Ask your teacher for a water molecule template

2. Cut out the three circles

3. Label the 2 small circles as hydrogen

4. Label the 1 big circle as oxygen

5. Color the 2 hydrogen atoms one color, and the 1 oxygen atom another color

6. Label the atom(s) that have a positive charge with a (+) sign

7. Label the atom(s) that have a negative charge with a (-) sign

8. Use a glue stick to attach the small circles to the larger circle as in the picture above

9. Ask your teacher for Velcro strips.

10. Find the fuzzier Velcro strips

11. Remove the paper from the back of the fuzzier Velcro strips and attach them to the back top edge of the atom(s) with a positive charge.

12. Find the rougher Velcro strip

13. Remove the paper from the back of the rougher Velcro strip and attach them to the front bottom edge of the atom with a negative charge.

Directions: In your group, examine the water molecules on your table and answer the questions below 1. How many atoms are there in a water molecule? _______ 2. Why does water have positive and negative sides? ___________________________________________________________________________________ ___________________________________________________________________________________ 2. Because water has positive and negative sides we say that it is ___________________ 3. When your two water molecules are together, which parts can stick to each other? ___________________________________________________________________________________ ___________________________________________________________________________________ 4. When molecules come together, positive charges are attracted to negative charges. How does your model show this? ___________________________________________________________________________________ ___________________________________________________________________________________ 5. Water also sticks really well to some other molecules, such as salt. A picture of a salt molecule is shown below. Explain why water would stick well to salt. ___________________________________________________________________________________ ___________________________________________________________________________________

   

HW17: Water Water Everywhere! ________Biology I

Homework 17: Properties of Water Biology I

Name: ___________________________ Date: ____________

Directions: Match the following properties of water with their correct definition

CONTINUED ON BACK!!!!!

 

POLARITY

COHESION

SURFACE TENSION

CAPILLARY ACTION

UNIVERSAL SOLVENT

ADHESION

A. Because water molecules stick together, they form a thin film on the surface of pools of water, on which some organisms can walk B. Water molecules are able to move against the force of gravity up plant stems C. Because of its polarity, water molecules are attracted and stick to other molecules, making water really good at dissolving a wide variety of substances D. Because of its polarity, water molecules are attracted and stick to one another E. A water molecule has slight positive and negative charges. This makes the molecule “sticky” F. Because of its polarity, water is attracted to and sticks to other substances

Directions: Describe in 1 – 2 sentences why each of the following unique properties of water is important to living things

Water is the universal solvent:

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Water is less dense as a solid than as a liquid

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Water molecules are attracted to one another (cohesion)

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Water molecules are attracted to other substances (adhesion)

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