Properties of Water

A water molecule (H2O), is made up of threethree atoms --- one oxygen and two hydrogen.

H

H

H

H

O

In each water molecule, the oxygen oxygen atom attracts moreatom attracts more than its "fair share" of electronselectrons

The oxygenoxygen end “acts” negativenegative The hydrogenhydrogen end “acts” positivepositive Causes the water to be POLARPOLAR However, Water is neutralneutral (equal

number of e- and p+) --- Zero Net Zero Net ChargeCharge

Attraction between the hydrogen atom on one water molecule and the oxygen atom on another=Hydrogen Bond

One hydrogen bond is weak , but One hydrogen bond is weak , but many hydrogen bonds are strongmany 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. At sea level, pure water boils at 100 °C and freezes at 0 °C. 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.

CohesionCohesion AdhesionAdhesion

High Heat of High Heat of VaporizationVaporization

High Specific HeatHigh Specific Heat Less Dense as a SolidLess Dense as a Solid

Attraction between particles of Attraction between particles of the same substance (the same substance ( why water why water is attracted to itself)is attracted to itself)

• Results in Surface tension (a Results in Surface tension (a measure of the strength of measure of the strength of water’s surface)water’s surface)Wax Paper ActivityWax 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 Attraction between twotwo different different substances.substances.

• Water will make hydrogen bonds with Water will make hydrogen bonds with other surfaces such as glass, soil, other surfaces such as glass, soil, plant tissues, and cotton. plant tissues, and cotton.

Capillary actionCapillary action-water molecules will -water molecules will “tow” each other along when in a thin “tow” each other along when in a thin glass tube.glass tube. Example: transpiration process which Example: transpiration process which

plants and trees remove water from plants and trees remove water from the soilthe 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 Amount of energy to convert 1g or a substance from a liquid to a gassubstance from a liquid to a gas

In order for water to evaporate, In order for water to evaporate, hydrogen bonds must be broken.hydrogen bonds must be broken.

As water evaporates, it removes a lot As water evaporates, it removes a lot of heat with it.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 absorbed and held by the vaporby the vapor.

• Amount of heat needed to raise or Amount of heat needed to raise or lower 1g of a substance 1° C.lower 1g of a substance 1° C.

Water resists temperature change, Water resists temperature change, both for heating and cooling.both for heating and cooling.

Water can absorb or release large Water can absorb or release large amounts of heat energy with little amounts of heat energy with little change in actual temperature.change in actual temperature.

• Ice is less dense Ice is less dense as a solid than as a liquid (ice floats)

• Liquid water has hydrogen bonds hydrogen bonds that are constantly being broken and constantly being broken and

reformed.reformed.

• Frozen water Frozen water forms a crystal-like latticecrystal-like lattice whereby molecules are set at fixed distances.

Water is Less Dense as Water is Less Dense as a Solida Solid

•Which is ice and which is Which is ice and which is

water?water?

Water is Less Dense as a Water is Less Dense as a SolidSolid

WaterWater IceIce

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-enzymeHydrate-waterOse-full of Philic-lovingPhobic-fearing

Carbo-coalDi-twoHydro-waterMono-onePoly-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 hydrogenExample: Methane (CH4)

Functional Group-A group of atoms within a molecule that interacts in predictable ways with other moleculesExample: Hydroxyl groups are HYDROPHILIC (literally meaning “water-loving”) meaning they attract water moleculesHowever, 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. Carbohydrates2. Lipids3. Proteins4. 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 labGraph 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