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