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The chemical reactions of all living things take place in an
aqueous (water based) environment. Thus, water is one of the most important compounds found in living
things!
Roughly 70 percent of an adult’s body is made up of water.
By the time a person feels thirsty, his or her body has lost over 1 percent of its total water amount.
Although a person can live without food for more than a month, a person can only live without water for approximately one week.
Your brain is 75-85% water and plays a vital role in your body's response to dehydration. It controls water intake through altering thirst and varying the water excretion from your kidneys.
Wate
r Fu
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acts
http://science.howstuffworks.com/environmental/earth/geophysics/h2o3.htm
http://www.healthy-water-best-filters.com/human-water-cycle.html
http://fiteats.wordpress.com/page/3/
http://www.mpip-mainz.mpg.de/documents/akbu/pages/ssci.html
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A. Water is the single most abundant compound in most living things B. Chemical formula =
H20--2 parts hydrogen--1 part oxygen
C. Bohr Model for water (covalent bonds)
D. Water is a POLAR covalent compound
2. Oxygen pulls on the e- greater than the H . . .so at any moment, the shared e- are more likely closer to the oxygen
3. What effect does “polar” have?
--water has a partial pos. pole and partial
neg. pole--like a magnet
E. Hydrogen Bonding 1. The partial + and partial – charges allow H2O molecules to attract to each other or stick together through Hydrogen Bonds2. Hydrogen bonds are WEAK
bonds that can be easily broken
3. H-bonds = responsible for H20 special properties . . .
Hydrogen Bonding Simulation
Example 2: Cohesion leads to water having a high surface tension . . . Due to the hydrogen
bonding of surface molecules to each other
Images from: http://understanding-biology.blogspot.com/2010/01/floating-paper-clip-cohesion-surface.html
b. Adhesion = attraction between molecules of
DIFFERENT substances Explains why microscope slides stuck together
3. Ice is less dense than
liquid water
Image from: http://www.wallpaperbase.com/landscape-iceberg.shtml
Properties of Water—seen in space
http://www.youtube.com/watch?v=o8TssbmY-GM
Simulation: Overview of water properties
Simulation found at: http://www.sumanasinc.com/webcontent/animations/content/propertiesofwater/water.html
surface tension =A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules
Electronegativity=The attraction of an atom for the electrons of a covalent bond Electronegativity is the tendency for an atom to pull electrons toward itself. Two atoms of the same element have equal electronegativities; in a covalent bond they share electrons equally, forming a nonpolar covalent bond.
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