Transcript The uniqueness of water http://www.youtube.com/watch?v

MONDAY, OCTOBER 13TH, 2014
Bio.A.1.2.2: Describe the unique properties of water and how these properties
support life on Earth
Objective: What makes water so important and unique?
Warmup:
***Brainstorm***
What properties do you remember about water? (ex.
Freezing point, density, chemical formula, etc)
Anything that you can remember…..
TUESDAY, OCTOBER 14TH, 2014
Bio.A.1.2.2: Describe the unique properties of water and how these properties
support life on Earth
Objective: What makes water so important and unique?
Warmup:
***Brainstorm***
What properties do you remember about water? (ex.
Freezing point, density, chemical formula, etc)
Anything that you can remember…..
THE UNIQUENESS OF WATER
HTTP://WWW.YOUTUBE.COM/WATCH?V=ASLUY2U1M-8
I. WHY IS WATER IMPORTANT TO ORGANISMS?
1. If you don’t live in it, you carry it with you: water makes up
60-95% of most organisms.
2. It plays many roles in the body:
• Allows molecules & ions to move, collide and dissolve
• Decreases concentration in blood for easier
movement/better pH levels
• Allows chemical reactions to occur
• Maintains a constant body temperature (homeostasis)
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
1. Water is polar (exhibits polarity)
• Polar molecule – molecule with an unequal distribution of
charge; each molecule has a negative (-) and positive (+)
end.
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
1. Water is polar (exhibits polarity)
• Shape (^) of water indicates oxygen attracts more e- than
hydrogen; oxygen acts (-) and hydrogen acts (+)
• Water’s overall charge = 10 p+
10 ezero
• Polar molecules are very attractive because (+) and (-) ends
function like a magnet
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
1. Water is polar (exhibits polarity) - Because water is like a
magnet:
• They (water molecules) attract:
ions
example: sodium (Na+) and chloride (Cl-)
polar molecules example: sugar (carbohydrate)
water
2. Water forms hydrogen bonds (bond between +/- ends of a
polar molecule)
• Characteristics:
 Weak bond – formed/broken easily
CUT OUT WATER MOLECULES
Part 1:
 Draw a model of one water molecule.
 1.) Show the number of protons, neutrons and
electrons in the shells of the atoms involved.

CUT OUT WATER MOLECULES
Part 2:
 Cut out a model of one water molecule.
 1.) Color the oxygen atoms of each water
molecule red.
 2.) Color hydrogen blue


3.) Indicate the relative charge of each side of the
water molecule by placing a plus or a minus on the
correct sides.
TUESDAY, OCTOBER 14TH, 2014
Bio.A.1.2.2: Describe the unique properties of water and how these properties
support life on Earth
Objective: What makes water so important and unique?
Warmup: What does it mean when we say that water is
POLAR?
Draw a picture or explain it please.
PART 3:

On your cut-outs page:

1.) Color the oxygen atoms of each water molecule red.
2.) Color hydrogen atoms blue.


3.) Indicate the relative charge of each side of the water
molecule by placing a plus or a minus on the correct sides.

4.) Cut out 5 molecules.

5.) Arrange them to show hydrogen bonds. Indicate the
hydrogen bonds between each water molecule by drawing
three black dots between them.
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
2. Water forms hydrogen bonds (bond between +/- ends of a
polar molecule)
• Characteristics:
 Weak bond – formed/broken easily
 Responsible for cohesion – intermolecular attraction
between like molecules (example: H2O - H2O)
 Produces surface tension so insects, leaves can float
on water
 Water molecules stick together to move against
gravity (capillary action)
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
2. Water forms hydrogen bonds (bond between +/- ends of a
polar molecule)
 Hold large molecules and H2O together. Adhesion – the
intermolecular attraction of unlike molecules
 Water forms droplets on leaves
 Water molecules stick together to move against
gravity (capillary action)
II. WHAT ABOUT WATER’S STRUCTURE ALLOWS
IT TO DO ALL THIS?
Like molecules
Unlike molecules
MINILAB – COHESION, ADHESION, SURFACE
TENSION
III. WHAT OTHER PROPERTIES DOES WATER
HAVE?
1. Has less density as a solid
• Water forms crystal-like bonds when it freezes, keeping the
molecules at fixed distances from each other
• Low density – less tightly packed
• Water expands when frozen and floats, allowing organisms
to live underneath
III. WHAT OTHER PROPERTIES DOES WATER
HAVE?
2. Is a universal solvent
• Dissolves many compounds such as carbohydrates and
some proteins
• Allows chemical reactions to occur
III. WHAT OTHER PROPERTIES DOES WATER
HAVE?
3. Has high heat of vaporization
• Amount of heat energy needed to change 1 g of 100˚C
boiling water to 100˚C steam
(you sweat and water evaporates off your skin to cool you)
III. WHAT OTHER PROPERTIES DOES WATER
HAVE?
4. Has high specific heat
• Amount of energy required to change 1 gram of water by
1˚C
(water resists change in temperature)
• Substances with H-bonds take longer to cool or heat than
those w/o
• Allows organisms to maintain a stable internal environment
(homeostasis)
• Allows water to resist temperature change
MORE ABOUT SOLUTIONS:

Water is known as the Universal Solvent:
 Solutions
 Solute
have 2 parts:
– what is being dissolved
 Solvent – what is doing the dissolving
• NaCl Solution and dissolving
MORE ABOUT SOLUTIONS:
 pH
Scale – Measures the amount of hydrogen ions in a
solution
 Low