1 PROPERTIES OF WATER Water is everywhere. It is in the air we breathe. It is in every cell in your body. Water is an unusual substance with special properties. 1.Why does water “bead up” (stick together) 2.Why does Ice float? 3.How does water rise from the roots of a redwood tree to the very top? 4.Why is water called the universal solvent? 5.Why don’t oil and water mix? Water is everywhere. It is in the air we breathe. It is in every cell in your body. Water is an unusual substance with special properties. 1.Why does water “bead up” (stick together) 2.Why does Ice float? 3.How does water rise from the roots of a redwood tree to the very top? 4.Why is water called the universal solvent? 5.Why don’t oil and water mix?

2 HYDROGEN BONDING DEFINE:  Electronegativity  Hydrogen bond  nonpolar  Polar covalent bond  Cohesion  Surface tension  Heat  Temperature  Density

3 Hydrogen Bonding Electronegativity- an atoms attraction for the shared electrons (covalent bond = sharing) IceLiquid

4 Hydrogen Bonding H 2 O = Polar Covalent Bond H-bonds: Weak & easily broken Oxygen - slightly (-) Hydrogen slightly (+)

5 POLARITY  NONPOLAR - EQUAL SHARING OF ELECTRONS (H 2 ), (O 2 ), (CH 4 ) Non-polar compounds are hydrophobic (water fearing) and not easily dissolved in water.  POLAR - UNEQUAL SHARING OF ELECTRONS ( H 2 O) Hydrophylic (water loving) - the polarity of water allows it to dissolve other polar molecules. LIKE DISSOLVES LIKE  NONPOLAR - EQUAL SHARING OF ELECTRONS (H 2 ), (O 2 ), (CH 4 ) Non-polar compounds are hydrophobic (water fearing) and not easily dissolved in water.  POLAR - UNEQUAL SHARING OF ELECTRONS ( H 2 O) Hydrophylic (water loving) - the polarity of water allows it to dissolve other polar molecules. LIKE DISSOLVES LIKE

6 Water-soluble protein Hydrophilic - like water

7 HYDROPHOBIC - OIL & WATER DON ’ T MIX!! Aerial images of the Deepwater Horizon oil spill taken from a US Coast Guard aircraft. April 20, Explosion and fire on drilling rig The Gulf of Mexico April 20, Explosion and fire on drilling rig The Gulf of Mexico

8 “Dissociation” of water Making ions (charged particles)

9 Surface tension Difficult to stretch or break the surface of a liquid Cohesion - like substances sticking together

10 Ice, water, vapor - phases of water Heat - amount of energy associated with the movement of the atoms & molecules in a body of matter Temperature - measure of the intensity of heat; the average speed of molecules Water resists temperature changes by absorbing a lot of heat.

11 Density of Water Density = mass/volume The reason ice floats is because a certain mass of ice occupies more space than the same mass of liquid water. Ice is one of the only substances that expands when it freezes

12 pH pH = – log [H+] Log scale means 10X change per unit! [H+]= M [H+]= M Adding or removing hydrogen ions changes the pH of a solution.

13 Buffers Buffers resist changes to the pH of a solution when H + or OH - is added to the solution. Buffers accept hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted.