The Properties of Water
The Mickey Mouse Molecule!
Hydrogen
Hydrogen
Oxygen
Structure of a Water Molecule
• Water is polar.
• A polar molecule is a molecule that
has an electrical charge.
• Water is made of:
• 2 Hydrogen Atoms and 1 Oxygen atom.
• The chemical formula for water is: H2O
• Hydrogen has a positive (+) charge and
Oxygen has a negative (-) charge.
4 Key Properties of Water
• Capillary Action
• Surface Tension
• Universal Solvent
• Specific Heat
Capillary Action
• Capillary action is the combined force of
•
attraction among water molecules and with the
molecules of surrounding materials.
Examples of Capillary Action of Water:
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Liquid rising inside a straw
Paper towel absorbing water
Wet jeans
Plant roots absorbing water
Sponge
Surface Tension
• Surface tension is the tightness across the
surface of water that is caused by the polar
molecules pulling on one another
• Examples of the surface tension of water:
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Raindrops forming beads on surface
Water strider
Paperclip Floating on Water
Drops of Water on a Penny
Skipping Rocks
Meniscus
Belly Flops
Jesus Lizard
Water Strider
Universal Solvent
• Solution: A mixture that forms when
one substance dissolves another.
• Solvent: substance that does the
dissolving.
• Solute: substance that gets dissolved.
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Water is the universal solvent because it dissolves so many
substances because of its high polarity.
Water can dissolve substances such as salt and sugar but
cannot dissolve oil.
Polar Dissolves Polar.
Specific Heat
•
•
•
Water requires a lot of heat (gain or loss) to
change its temperature due to the strong
attraction among water molecules.
Specific heat is the amount of heat needed to
increase the temperature of a substance by 10C
Example of specific heat:
- Water temperature vs. sand temperature at the beach during the day.
Why does water have a high
specific heat?
– Water’s high specific heat is due to the
strong attraction among water
molecules.
– The molecules are stuck together
and it takes a lot of energy to break
the strong bonds of the water
molecules.
Changing State
• Water exists in 3 forms:
– solid
– liquid
– gas
solid
liquid
gas
Molecule Movement
Molecules move the slowest
in a solid.
Solid-molecules are
close together
Molecules move the fastest
in a gas.
Gas-molecules move
freely; they are spread
apart
Phase Changes
• Melting-water changes from a solid to a
liquid
– Example: Ice melts into water
• Freezing-water changes from a liquid to a
solid
– Example:
Water freezes into ice
Melting
Solid
Liquid
Freezing
Phase Changes
• Evaporation- process by which molecules at the
surface of a liquid absorb enough energy to
change to the gaseous state
– Example: boiling water, hair air-drying, wet clothes
drying on a clothesline outside, puddle drying up
• Condensation-process by which a gas changes
to a liquid
– Example: water droplets on the outside of a glass
fogging up a window
Evaporation
Liquid
Condensation
Gas
Phase Changes
Phase Change Diagram