Water is ESSENTIAL to life.

Living organisms are composed mostly of water.

• Humans – 76%• Jellyfish – 90%• Dried beans – 50%

• Is NOT 180 degrees

(H—O—H)

• IS a little more than

a 90 degree angle.

• Water is Polar – One end is positive, one end is negative.

The +/- attraction between the H (+) of one water molecule and the O (-) of the adjacent water molecule.

Oxygen is slightly negative

Hydrogen is slightly positive

Polarity & Hydrogen bonds http://videos.howstuffworks.com/hsw/19233-simply-science-atoms-sharing-electrons-video.htm

1. “Universal Solvent”2. Freezes & Floats3. Cohesion (Surface tension)4. Adhesion (Capillary action)5. High heat of vaporization6. High heat of fusion

SolutionA mixture of…

• Solute– A substance that is put INTO the solvent

to dissolve.

• Solvent– Substance that does dissolves the solute– Water - Universal Solvent

SUSPENSION

Ever hear…

Oil & water don’t mix???

Water dissolves polar (ionic) substances:

– SALT (NaCl)

Water dissolvesnon-polar molecules:

– O2Helps fish survive– CO2

Helps algae survive

BLOOD is 95% water. Ions (NaCl) dissolve in blood (SOLUTION).

Imagine if ice didn’t float on top of a lake…

Ice is dense less than water

Ice has spaces between its water molecules

Ice acts as an insulator to allow the water below to remain a liquid.

The water strider bug relies on surface tension to survive.

The hydrogen bonds pull a water molecule in every direction by adjacent molecules.

Water molecules at the surface are not pulled from above.

This produces a “tension”.

What substance “broke” the tension in the Water Lab?

COHESION – The attraction between water molecules make them “stick” together.

ADHESION – The attraction between a water molecule and another substance.

CAPILLARY – Any thin long tube.

CAPILLARY ACTION – DUE TO cohesion & adhesion Water acts like a magnet and pull itself up against gravity.

Living things have capillary tubes:• Animals - blood vessels• Plants – xylem/phloem

• From - roots• To - leaves

Which substance has greater ADHESIVE properties?

COHESION: Water “sticks” to water

ADHESION: Water “sticks” to another substance

MercuryRed dyed water

Compared to other liquids it takes a lot of energy to evaporate water.

(Less evaporation leaves more water available for living things)

• High heat of fusionLarge bodies of water change temperature more slowly than air does.

(Lakes/ponds stay warmer, longer for living things)