Properties of Water

three  A water molecule (H 2 O), is made up of three atoms --- one oxygen and two hydrogen. H H H H O

oxygen atom attracts more electrons  In each water molecule, the oxygen atom attracts more than its "fair share" of electrons oxygennegative  The oxygen end “acts” negative hydrogenpositive  The hydrogen end “acts” positive POLAR  Causes the water to be POLAR neutral Zero Net Charge  However, Water is neutral (equal number of e- and p+) --- Zero Net Charge

 Attraction between the hydrogen atom on one water molecule and the oxygen atom on another=Hydrogen Bond  One hydrogen bond is weak, but many hydrogen bonds are strong

 Single most abundant compound in most living things.  Water expands as it freezes = meaning ice is less dense then liquid water. 100 °C and freezes at 0 °C.  At sea level, pure water boils at 100 °C and freezes at 0 °C.  The boiling temperature of water decreases at higher evaluations (lower atmospheric pressure).  For this reason, an egg will take longer to boil at higher altitudes.

 Cohesion  Adhesion  High Heat of Vaporization  High Specific Heat  Less Dense as a Solid

 Attraction between particles of the same substance (why water is attracted to itself)  Attraction between particles of the same substance ( why water is attracted to itself) Results in Surface tension (a measure of the strength of water’s surface) Results in Surface tension (a measure of the strength of water’s surface)  Wax Paper Activity

 Adhesion (water to other) and Cohesion (water to water)  Its almost like water forms a skin on the surface Pepper Activity

Attraction between two different substances. Attraction between two different substances. Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.  Capillary action-water molecules will “tow” each other along when in a thin glass tube.  Example: transpiration process which plants and trees remove water from the soil Examples: Microscope Slide/Penny Activity /Celery

Which gives water the ability to “climb” structures

Form spheres & hold onto plant leaves Attach to a silken spider web

 Amount of energy to convert 1g or a substance from a liquid to a gas  In order for water to evaporate, hydrogen bonds must be broken.  As water evaporates, it removes a lot of heat with it.

 Water vapor  Water vapor forms a kind of global ‘‘blanket” which helps to keep the Earth warm.  Heat radiated from the sun  Heat radiated from the sun warmed surface of the earth is absorbed and held by the vapor by the vapor.

Amount of heat needed to raise or lower 1g of a substance 1° C. Amount of heat needed to raise or lower 1g of a substance 1° C.  Water resists temperature change, both for heating and cooling.  Water can absorb or release large amounts of heat energy with little change in actual temperature.

Ice is less dense Ice is less dense as a solid than as a liquid (ice floats) hydrogen bonds constantly being broken and reformed. Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water crystal-like lattice Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

Water is Less Dense as a Solid Which is ice and which is water?Which is ice and which is water?

Water is Less Dense as a Solid WaterIce

 Why are carbon atoms so common in living things?  One carbon atom can form 4 covalent bonds with other atoms.  Covalent bonds (share electrons) enable the carbon atoms to bond to each other, which results in a variety of important organic compounds.  Can be straight chained, branched, or in a ring shape that lead to the diversity of life. Figure 25

 Ase-enzyme  Hydrate-water  Ose-full of  Philic-loving  Phobic-fearing

 Carbo-coal  Di-two  Hydro-water  Mono-one  Poly-many

 Most carbon based molecules are classified as ORGANIC Molecules  In contrast-non-carbon based molecules such as water, oxygen, and ammonia are classified as INORGANIC Molecules

 HYDROCARBONS-organic molecules that are composed of only carbon and hydrogen  Example: Methane (CH 4 )

 Functional Group-A group of atoms within a molecule that interacts in predictable ways with other molecules  Example: Hydroxyl groups are HYDROPHILIC (literally meaning “water-loving”) meaning they attract water molecules However, if they are not “water- loving” they are HYDROPHOBIC (literally meaning “water fearing”)

 Large molecules are built from many similar, smaller molecular units called MONOMERS  When monomers link together and make a long chain these are called MACROMOLECULES or POLYMERS.  Example: The protein that makes up a spiders web, every living cell has thousands of different kinds of polymers

 IMPORTANT: Life’s large molecules are classified into four main categories:  1. Carbohydrates  2. Lipids  3. Proteins  4. Nucleic Acids

 Each time a monomer is added to a chain, a water molecules is released; this is called a DEHYDRATION REACTION  Cells break bonds between monomers by adding water to them, the reverse of dehydration; HYDROLYSIS REACTION

In the dehydration reaction, two monomers bond to each other, making a polymer chain longer. The hydroxyl group of one monomer reacts with a hydrogen atom from the other monomer. The reactions involved ultimately release a water molecule.

In the hydrolysis reaction, the addition of a water molecule breaks the polymer chain.

Regular or Extra Strength? 1.pH scale ranges from ___ to ____ 2.Acid range? H or OH ions? 3.Base range? H or OH ions? 4.Neutral? 5.How could you improve the lab?

 Line Graph….be sure to include title, labels and a key  Date Table 1…needs to be retyped or done neatly on a new sheet of paper…DO NOT just staple the paper from your lab  Graph and Table DO NOT have to be typed but they need to be neat and legible  1 paragraph describing data…what were your results..be sure to include some numbers