Water and the Water and the Chemistry of Life Chemistry of Life

Water FactsWater Facts• There is the same amount There is the same amount

of water on Earth today as of water on Earth today as there was 3 billion years there was 3 billion years ago. ago.

• Three percent of the water Three percent of the water on Earth is freshwater and on Earth is freshwater and only 1 % is avaiIable for only 1 % is avaiIable for human consumption. human consumption.

• Sixty-six percent of a Sixty-six percent of a human being is water. human being is water.

• Seventy-five percent of the Seventy-five percent of the human brain is water. human brain is water.

• Seventy-five percent of a Seventy-five percent of a living tree is water. living tree is water.

• You could survive about a You could survive about a month without food, but month without food, but only 5 to 7 days without only 5 to 7 days without water. water.

Water FactsWater Facts

Recall some of the water facts in slide Recall some of the water facts in slide one. one.

• Jot these down. Jot these down.

Turn to your partner and explain Turn to your partner and explain the importance of water in your life.the importance of water in your life.

The Water MoleculeThe Water Molecule

• The water The water molecule contains molecule contains one oxygen atom one oxygen atom and two hydrogen and two hydrogen atoms.atoms.

Properties of WaterProperties of Water

Water is PolarWater is Polar Water is polar because oxygen is a Water is polar because oxygen is a

“bully” and does not share the “bully” and does not share the electrons.electrons.

Water is PolarWater is Polar

• Oxygen is negative with more Oxygen is negative with more electrons and Hydrogen is positive electrons and Hydrogen is positive with less electrons.with less electrons.

Water Forms Hydrogen Water Forms Hydrogen BondsBonds• Water molecules Water molecules

attract each other attract each other because of because of Oxygen’s (-) charge Oxygen’s (-) charge and Hydrogen’s (+) and Hydrogen’s (+) charge.charge.

• Hydrogen bonds Hydrogen bonds hold water hold water molecules together.molecules together.

Water Forms Hydrogen Water Forms Hydrogen BondsBonds

2. Draw one water molecule and label 2. Draw one water molecule and label the the

(+ H) and the (- O).(+ H) and the (- O).

Draw two more water molecules and Draw two more water molecules and show them connected together with show them connected together with hydrogen bondshydrogen bonds

Hydrogen Bonds Hydrogen Bonds and the Titanicand the Titanic• Hydrogen bonds sank Hydrogen bonds sank

the the TitanicTitanic. . • The reason ice floats is The reason ice floats is

because of hydrogen because of hydrogen bonding.    In other bonding.    In other words, ice is less dense words, ice is less dense than liquid water and will than liquid water and will float on the surface of float on the surface of the liquid.  Throw in one the liquid.  Throw in one really big chunk of ice really big chunk of ice and a cruise ship, and and a cruise ship, and you begin to see the you begin to see the problems that can arise.   problems that can arise.  

CohesionCohesion

• Cohesion is the Cohesion is the attraction of the attraction of the same type of same type of molecules to each molecules to each other. other.

• Water molecules Water molecules stick together and stick together and “hold hands” with “hold hands” with hydrogen bondshydrogen bonds

CohesionCohesion

• Cohesion explains Cohesion explains “wetness”. Water “wetness”. Water molecules stick molecules stick together and form together and form drops.drops.

• Cohesion explains Cohesion explains why insects can why insects can walk on a lake’s walk on a lake’s surface.surface.

AdhesionAdhesion

• Adhesion is the Adhesion is the attraction of attraction of molecules between molecules between two differenttwo different substances. substances.

• Example: The Example: The attraction of water attraction of water molecules to a molecules to a glass. glass.

AdhesionAdhesion

• Adhesion causes Adhesion causes “this”. “this”.

#3#3. . Name the line Name the line and the equipment.)and the equipment.)

• Adhesion causes Adhesion causes water to rise in a water to rise in a strawstraw

Adhesion or Cohesion??Adhesion or Cohesion??

• Your teacher will put a drop or two of Your teacher will put a drop or two of water on your desk.water on your desk.

#4. The water clinging to your desk is #4. The water clinging to your desk is an example of ____________an example of ____________

#5 The water forming drops is an #5 The water forming drops is an example of __________________example of __________________

Adhesion or Cohesion??Adhesion or Cohesion??

#6 Water rising in #6 Water rising in plants from roots to plants from roots to leaves.leaves.

#7 Animals walking on #7 Animals walking on surface water tension.surface water tension.

#8 Colored celery #8 Colored celery leaves.leaves.

Water is the Universal Water is the Universal SolventSolvent

Water is polar and Water is polar and can dissolve both can dissolve both salts, sugars, and salts, sugars, and other molecules.other molecules.

Water is the Universal Water is the Universal SolventSolvent

#9 Why is water such a good solvent?#9 Why is water such a good solvent?

#10 What could you do to dissolve a #10 What could you do to dissolve a solute in water faster? solute in water faster?

OR how could you speed up the OR how could you speed up the dissolving of sugar in water?dissolving of sugar in water?

Water Molecules Can SplitWater Molecules Can Split

• A water molecule can A water molecule can split and form ions.split and form ions.

• HH220 H0 H++ + OH + OH--

• An ion is a charged An ion is a charged atom. (+ or -)atom. (+ or -)

Water Molecules Can SplitWater Molecules Can Split

#11 What is the charge of the (H )ion?#11 What is the charge of the (H )ion?

#12 What is the charge of the (OH) #12 What is the charge of the (OH) ion?ion?

Water and AcidsWater and Acids

• Acids form HAcids form H++ ions ions in a water solution.in a water solution.

• Acid solutions have Acid solutions have high high concentrations of concentrations of HH++ ions and have a ions and have a pH value less than pH value less than 77 . .

Water and BasesWater and Bases

• Bases form OHBases form OH-- ions ions in a water solution.in a water solution.

• Basic solutions have Basic solutions have high concentrations high concentrations of OHof OH-- ions and have ions and have a pH value greater a pH value greater than than 77 . .

Acids and BasesAcids and Bases#13. Acids form _____ions#13. Acids form _____ions

#14. Bases form _____ions#14. Bases form _____ions

#15. Draw this number line and label #15. Draw this number line and label acids, bases, and neutral. Write acids, bases, and neutral. Write examples of acids and bases along examples of acids and bases along your number line.your number line.

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The Water CycleThe Water Cycle

The Water CycleThe Water Cycle

• Earth's water is always in movement, and the Earth's water is always in movement, and the water cycle, also known as the hydrologic water cycle, also known as the hydrologic cycle, describes the continuous movement of cycle, describes the continuous movement of water on, above, and below the surface of water on, above, and below the surface of the Earth. Since the water cycle is truly a the Earth. Since the water cycle is truly a "cycle," there is no beginning or end. Water "cycle," there is no beginning or end. Water can change states among liquid, vapor, and can change states among liquid, vapor, and ice at various places in the water cycle, with ice at various places in the water cycle, with these processes happening in the blink of an these processes happening in the blink of an eye and over millions of years. eye and over millions of years.

The Water CycleThe Water Cycle

# 16 Write some of the stages in the # 16 Write some of the stages in the water cycle.water cycle.

Turn to your partner and explain how Turn to your partner and explain how water cycles from drop to drop.water cycles from drop to drop.

The Water CycleThe Water Cycle

• Although the balance of water on Earth Although the balance of water on Earth remains fairly constant over time, remains fairly constant over time, individual water molecules can come individual water molecules can come and go in a hurry. The water in the apple and go in a hurry. The water in the apple you ate yesterday may have fallen as you ate yesterday may have fallen as rain half-way around the world last year rain half-way around the world last year or could have been used 100 million or could have been used 100 million years ago by Mama Dinosaur to give her years ago by Mama Dinosaur to give her baby a bath. baby a bath.

HOMEWORK-Chapter 2.2HOMEWORK-Chapter 2.21. Complete the following four square analogy for water:

Water is….. Its properties are….

Water is important because… I have questions/am confused about…

2. Write a summary about the properties of water using the following words:

Polar Hydrogen bonds CohesionAdhesion Solvent Surface Tension