UNIQUE PROPERTIES OF WATER Pages 24 - 26
Mar 29, 2015
UNIQUE PROPERTIES OF
WATERPages 24 - 26
POLAR MOLECULE A molecule with
opposite charges on different ends
A molecule with a charge distribution
ELECTRONEGATIVITY The tendency for an
atom to pull electrons toward itself
Oxygen is more electronegative than hydrogen, so the electrons spend more of their time closer to the oxygen atom giving it a slight negative charge and leaving the hydrogens with slight positive charges
COHESION Water attracted
to water Hydrogen
bonding between adjacent water molecules allows water molecules to bond with other water molecules
COHESION ALLOWS FOR TRANSPIRATION
COHESION ALLOWS FOR HIGH SURFACE TENSION
HIGH SPECIFIC HEAT It takes a great
deal of heat energy to change the temperature of water or to make water vaporize; therefore, large bodies of water can moderate temperature changes
EVAPORATIVE COOLING When sweat evaporates
from the skin, the water molecules that transition from liquid sweat to gaseous water vapor are the fastest moving molecules. As they shift phases it takes lots of energy and heat is given off. The water that remains is slower moving and much cooler. This results in lowering the body temperature.
FREEZING POINT As water freezes
each molecule forms stable hydrogen bonds with 4 other water molecules
The freezing point for water is 0°C
DENSITY Highly structured ice is less dense than
water and floats on top of water This allows life in bodies of water to
survive cold temps
SOLVENT OF LIFE Because of its
polar nature (+ and – charges) water can pull apart/ dissolve many other polar substances like sugar and ionic compounds like salt