Dihydrogen Monoxide (H20) Properties of Water

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Dihydrogen Monoxide(H20)Properties of Water
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Question?

• What molecule Is the most common In living Cells?
• Water - most cells are 70 - 95
  
  water.

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The Water Planet
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Properties Of Water

• Be ready and able to discuss several of the
  following properties.
• Focus on definitions and examples.

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What Makes Water Unique

• 1) Water is polar
• 2) Hydrogen Bonding

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Water is Polar

• Oxygen is bonded to 2 hydrogens by polar covalent
  bonds
• Causes hydrogen atoms to have a partial charge
  and oxygen to have a partial charge.

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Electrons spend more time with Oxygen
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Hydrogen Bonding

• A Hydrogen on one H20 molecule sticks to the
  Oxygen on another H20 molecule

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Polarity and Hydrogen Bonding Causes

• 5 Properties of Water
• 1) Cohesion
• 2) Adhesion
• 3) High Capacity to Absorb Heat
• 4) Water Expands when
  Frozen
• 5) Good Solvent

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1) Water Is Cohesive

• Water sticks to water.
• Why?
• Because the polarity of water creates pos and neg
  charges (makes it sticky).
• Water sticks to water through hydrogen bonds

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How does this affect Life?

• Creates surface tension.
• The surface of water is difficult to stretch or
  break.

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2) Water is Adhesive

• Water sticks to other molecules.
• Why?
• Hydrogen bonding - sticky Hydrogens bond to
  other sticky molecules

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How does this affect Life?

• Plants use adhesion and cohesion to transport
  water throughout plant.
• Capillary Action Plants

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3) Water Has A High Capacity to Absorb Heat

• It takes a lot of thermal energy to raise the
  temperature of water.
• Why?
• It takes a lot of energy to break water
  molecules apart (break H bonds)

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Temperature

• Measures the average speed of the molecules.

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Celsius Scale

• Will be used for most of our temperature
  measurements.
• O oC - water freezes
• 100 oC - water boils
• 37 oC - human body
• 25C room temperature
  

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How does this affect Life?

• Water can absorb and store a huge amount of heat
  from the sun.
• Stabilizes earth temperatures - climate
  moderation
• Example Desserts are really hot in day and
  really cold at night
• Organisms are able to survive temperature
  internal and external changes.
• Example When running you dont overheat because
  you are 70 water

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Fig. 3-5
San Bernardino 100
Burbank 90
Santa Barbara 73
Riverside 96
Los Angeles (Airport) 75
Santa Ana 84
Palm Springs 106
70s (F)
80s
Pacific Ocean
90s
100s
San Diego 72
40 miles
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4) Water Expands When It Freezes

• The distance between water molecules INCREASES
  from the liquid to the solid form.
• Why?
• Hydrogen bonding and waters bent shape

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Freezes in hexagonal shape makes it less dense
when a solid
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Solids and Liquids
Water
Benzene
Floats
Sinks
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How does this affect Life?

• Top layer of ice insulates water beneath
• Ponds/Lakes dont completely freeze
• Aquatic life can live under ice.

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5) Water Is A Good Solvent

• Water will dissolve many solids into a solution.
• Why?
• Sticky hydrogens bond to other substances
  and pull them apart.

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Hydrophilic Materials

• Materials that dissolve in water.
• Hydro - water
• philic - to like or love
• Have ionic or polar regions (sticky regions) on
  their molecules for H bonds.

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Hydrophobic

• Materials that repel water.
• Hydro - water
• phobic - to fear
• Have non-polar covalent bonds no sticky ends
  for water to stick to.
• . Ex - lipids.

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How does this affect Life?

• Many examples
• Foods need to be broken down
• Saliva contains water and helps to break foods
  apart.

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Without Water Life Would Not Be Possible!!