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WaterWaterLiving organisms
depend on the uniqueproperties of water.
H2O MoleculeH2O Molecule• 2 atoms of hydrogen: Atomic #
= 1• How many protons and
electrons?
• 1 atom of oxygen: Atomic # = 8• How many protons and
electrons?
• 2 atoms of hydrogen: Atomic # = 1
• How many protons and electrons?
• 1 atom of oxygen: Atomic # = 8• How many protons and
electrons?
Electron Configuration of
Water
Electron Configuration of
Water
Space-Fill Model of Water
Space-Fill Model of Water
Water Molecule Polarity
Water Molecule Polarity
• Oxygen is a bigger atom with 8 protons and pulls more forcefully on the electrons than hydrogen does.
• This creates positive (+) and negative (-) poles on the molecule.
• Oxygen is a bigger atom with 8 protons and pulls more forcefully on the electrons than hydrogen does.
• This creates positive (+) and negative (-) poles on the molecule.
Polar Covalent Bonds
Polar Covalent Bonds
• Bonds that form when electrons are shared unevenly.
• Areas of the molecule are slightly charged, although water molecules remain neutral.
• Bonds that form when electrons are shared unevenly.
• Areas of the molecule are slightly charged, although water molecules remain neutral.
Hydrogen Bonds
Hydrogen Bonds
• Hydrogen (+) of one molecule is attracted to a nearby atom (-) of a different molecule of water or other substance
• Hydrogen (+) of one molecule is attracted to a nearby atom (-) of a different molecule of water or other substance
Hydrogen Bonds are WeakHydrogen Bonds are Weak
• Electrons are not shared, gained, or lost
• Temporary bonds form
• Bonds are easily broken
• Electrons are not shared, gained, or lost
• Temporary bonds form
• Bonds are easily broken
Hydrogen Bonds form in Water and DNA
Hydrogen Bonds form in Water and DNA
CohesionCohesion
AdhesionAdhesion
Surface TensionSurface Tension
Special Properties of Water
Special Properties of Water
• Cohesion: Attraction of same molecules to each other
• Adhesion: Attraction of different molecules to each other
• Surface Tension: The force needed to break the surface of a liquid due to cohesion
• Cohesion: Attraction of same molecules to each other
• Adhesion: Attraction of different molecules to each other
• Surface Tension: The force needed to break the surface of a liquid due to cohesion
Polar and Non-Polar Molecules
Polar and Non-Polar Molecules
Polar molecules repel non-polar
molecules
Polar molecules repel non-polar
molecules•Water is polar• Oil is non-polar
•Water is polar• Oil is non-polar
The Cell Membrane has Polar and Non-Polar
Regions
The Cell Membrane has Polar and Non-Polar
Regions
Capillary Action: How Water Moves up
Plants
Capillary Action: How Water Moves up
Plants• Plant tubes
(xylem) are made of cellulose which is polar.
• Water molecules are attracted to the sides of thin tubes of xylem.
• Plant tubes (xylem) are made of cellulose which is polar.
• Water molecules are attracted to the sides of thin tubes of xylem.
Soap and WaterSoap and Water• The surface of water has high tension
due to the strong force of cohesion.
• Soap molecules have two ends. One end is attracted to water and the other end repels water.
• Soap separates the water molecules and breaks the surface tension.
• The surface of water has high tension due to the strong force of cohesion.
• Soap molecules have two ends. One end is attracted to water and the other end repels water.
• Soap separates the water molecules and breaks the surface tension.
What Happened to the Pepper?
What Happened to the Pepper?
• Pepper floats on the water.• Soap break the surface tension of
water by getting “between” water molecules.
• Pepper scatters as water’s hydrogen bonds are broken near the soap.
• Pepper floats on the water.• Soap break the surface tension of
water by getting “between” water molecules.
• Pepper scatters as water’s hydrogen bonds are broken near the soap.
How many drops of water can you place on a penny?How many drops of water can you place on a penny?
http://programs.northlandcollege.edu/biology/Biology1111/animations/hydrogenbonds.html
http://programs.northlandcollege.edu/biology/Biology1111/animations/hydrogenbonds.html