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

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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

a.Cohesion= attraction between molecules of the

SAME substance Explains why water beads up

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

Example of both cohesion and adhesion of water working together . . .

capillary action in plants

TedEd video clip on water

Water acts like a heat buffer for the globe.

3. Ice is less dense than

liquid water

Image from: http://www.wallpaperbase.com/landscape-iceberg.shtml

“Universal solvent”

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.