Molecules are small particles that make up matter. They are made up of even tinier particles called atoms. Some molecules have as few as two atoms while some have millions of atoms. There are more molecules in your body than there are stars in our universe!

Each molecule has its own special shape that allows it to interact with other molecules. These interactions between molecules make it possible for living things to move, sense, reproduce and just be alive.

The word polymer means "many parts". A polymer is a large molecule made up of many smaller molecules linked together like a long chain.

Polymers are found almost everywhere in nature. Certain types of polymers called proteins make up hair, feathers, cartilage, and other body parts. Starches in our food are polymers. Another polymer called cellulose makes up wood, leaves, and other plant parts. Bone, horn, cotton, silk, rubber, paper, and leather all come from naturally-occurring polymers. DNA, the genetic blueprint that defines people and other living things, is a naturally-occurring polymer.

There are many manmade polymers as well. Fabrics such as rayon and polyester, polystyrene (used in styrofoam coffee cups), and PVC (used in pipes) are common examples of these artificially-occurring polymers.

Polymers have many distinct properties which allow them to be used for lots of different things including car parts,food storage, electronic packaging, optical components, protective coverings, and adhesives.

Materials:
-ziplock bag
-sharpened pencil
-water
-wooden skewer
-balloon
-vegtable oil

What To Do:
Fill the plastic bag almost full of water. Seal the bag. Hold the bag over a sink or bucket or over the ground outside. While you hold the bag, your partner should slowly push the point of the pencil through the side of the plastic bag and into the water. Did any water spill? Don't take the pencil out. Why do you think very little or no water spills? Look closely at the plastic bag surrounding the pencil. How would you describe the way the plastic bag fits around the pencil? Do you think the pencil can go all the way through the water and out the other side of the bag with no water spilling? Ask your partner to slowly push the pencil all the way through the other side of the bag. What happened?

Try to poke a wooden skewer through a balloon without popping it. This takes some practice! Rub a little vegetable oil along the length of the skewer. Carefully poke it through the thick, unexpanded material near the knot of the balloon. Then twist the skewer as you move it through the balloon. Poke the skewer out through the thickest part at the other end of the balloon. Is there anything about long thin polymer strands that might help explain why the pencil can do this?

How it works:
The plastic bag and the balloon are very flexible because of the long, stretchy molecules called polymers from which they are made. When a sharp pencil or skewer is poked through, some of the long thin polymer strands shift over and then flex enough to squeeze back around the pencil or skewer. This flexibility creates somewhat of a seal so that the water or air does not spill out much. Rubber tires on cars also work this way. A gummy layer on the inside of the tire seals around any nails or sharp objects that poke directly into the tire.

Materials:
-skim milk (whole milk won't work because the fat molecules separate with the casein and interfere with the glues structure, making it too weak)
-vinegar
-glass jar
-cheesecloth
-baking soda

What To Do:
Place 1/2 cup skim milk in a glass or jar. Add 1/8 cup vinegar and stir for a few minutes. Small lumps, which are curds, will form. Let them settle for a few minutes, then pour off as much liquid (the "whey") as possible. Filter the remainder through a cheesecloth until the curds are dry, and return them to the glass. Add about 1/2 teaspoon baking soda (for neutralization) to the curds, and mix. You should see some slight foaming. Keep mixing until the curd becomes smoother and more liquid. The curd has now become glue. If the mucture is too thick, add a few drops of water. If it is too lumpy, add another pinch of baking soda, and stir. You should see some foaming. Don't be afraid to experiment by adding more water or baking soda to improve the consistency of your glue. The finished product can vary from a thick liquid to a thick paste. This depends on how much curd there is, and how much water and baking soda are used. Use your new glue to paste together pieces of paper. It may take 15-30 minutes to dry depending on how much you use, but it should work as well as a traditional white school paste. Cover your cup of glue with plastic wrap and let it sit for a few hours, or even overnight. The consistency should become smoother and clearer. Dispose of the wet glue in the trash within 24-48 hours or it will start to spoil and smell like spoiled milk.

How it works:
When you added the vinegar to the milk, it caused the milk's protein, the polymer casein, to separate from the liquid part of the milk and clump together to form solids. The baking soda neutralizes the acid in the vinegar. When the curd no longer has acid in it, it returns to a more liquid form. The liquefied casein protein is a natural glue. The foaming you see when the baking soda is added to the curd is carbon dioxide gas, which is made when the baking soda reacts with the acid in the vinegar. Casein has a lot of industrial uses. It is used in food products such as non-dairy creamers and as a raw material in adhesives, paints, and even plastics.

WHAT HOLDS MOLECULES TOGETHER?
Chemicals are substances held together by bonds. Some bonds are stronger than others. Two types of bonds are covalent bonds (bonds formed by the sharing of electrons) and ionic bonds (bonds formed by the attraction of oppositely charged ions). In this activity you can observe and stretch bonds. You will actually see how some substances are held together.

Materials:
-one sheet each of newspaper, typing paper, construction paper, writing paper, and cardboard
-gummy candy
-candy containing chewy caramel
-marshmallow
-standard (metric) ruler

What To Do:
Hold the sheet of newspaper so that it looks as if you are holding a rectangle. With your hands, pull (in opposite directions) both ends of the paper. Notice what happens. Rip the sheet of newspaper in half. Notice how easily it rips and the shape formed on each piece of paper after it is ripped. Repeat steps 1 and 2 with each type of paper. Carefully and slowly stretch a marshmallow to the point where it is ready to separate into two pieces. Using the standard (metric) ruler, measure to the nearest inch (centimeter) the farthest distance that the bonds in the marshmallows stretched. Repeat steps 4 and 5 with a piece of gummy candy and with a piece of candy containing chewy caramel.

Two important polymeric materials are elastomers and plastics. Elastomers allow movement of individual polymer molecules. These materials can be stretched a large amount when a force is applied to them, and can return to their original shape (or almost) when the force is released. Plastics are a large group of man made polymers containing many polymer molecules locked into place. In both types of polymers, secondary bonds hold groups of these polymer chain molecules together to form a polymeric material. If the molecules aren't stuck to each other too much, the material can be stretched, and is called an elastomer. But if the molecules are well-attached to each other, you get a plastic.

We can use the example of cooked spaghetti to understand this better. When a pile of freshly cooked spaghetti comes out of the hot water and into the bowl, the strands flow like a liquid from the pan to the bowl. The long "molecules" are slippery and slide past each other easily. The substance acts like a liquid because the "molecules" flow. After awhile, the water drains off of the pasta and the strands start to stick together. The spaghetti takes on a rubbery texture. The "molecules" stick together at a few places along the strand. Then the substance behaves like a rubbery solid called an elastomer. Wait a little while longer for all of the water to evaporate, and the pile of spaghetti turns into a solid mass -- drop it on the floor and watch it bounce. The "molecules" are stuck together, just like a plastic.

Materials:
- Elmer's Glue® (glue-all or school glue)
- Borax (Borax brand powdered soap)
- Zipper-lock bag (quart size)
- Empty plastic soda bottle with cap
- Water

What To Do:
Add 1 tablespoon of Borax powder to 1 cup of water. Remember that one cup of Borax water will make many batches of Slime. Measure 2 tablespoons of Elmer's Glue into a plastic cup. Add 1 tablespoon of plain water to the cup and mix. The additional water makes the glue very runny. Add 1 tablespoon of the Borax water to the bag of watered down glue. Mix completely. What is happening to the runny glue? What changes are taking place? Is it a solid? Is it a liquid? What is this slimy stuff?

How it works:
When you poured the Borax into the glue solution, your blob of glue did not act like regular glue anymore. It became stretchier and was not as sticky. This change happened because of a change with the polymer in the glue. The polymer in Elmer's glue is a liquid polymer called polyvinyl acetate.The molecule strands are not joined so they slide past each other as the glue flows. A chemical in the Borax solution connects the polyvinyl acetate molecules to make a large network - rather like a flexible scaffolding-so they can't slide as much. This is called cross-linking. This turns the liquid polymer into an elastomer which is soft or stiff depending on the amounts of glue, water, and Borax you use. The molecules aren't fixed in place so they can still be stretched, unlike a hard plastic.

Materials:
-glue (wood glue works well but white glue will work too)
-Epsom salts
-water
-measuring spoons
-plastic spoon
-2 small cups
-waxed paper

What To Do:
In one cup, put 1/2 tsp Epsom salt and 1/2 tsp water, stir to dissolve salt. (NOTE: It may not all dissolve.) In the other cup, put 1 tablespoon glue. Add the Epsom salt water to the glue and stir. Watch as your new material starts to form. Pull out the putty and put it on the waxed paper. You can experiment with it to find out more about its properties. You can store the new putty in a plastic bag.

How it works:
The glue with Epsom salts polymer is similar to the Borax polymer. The way that these strands are connected by the other chemical gives each polymer its unique characteristics.

The slime and putty are also examples of non Newtonian fluids. All fluids have a property known as viscosity. Viscosity is a big word which means "resistance to flow." The more viscous a substance, the slower it flows. Ketchup is more difficult to pour than water because ketchup is more viscous. And peanut butter is more viscous than ketchup.

Back in the 1700s, there was a scientist named Isaac Newton who studied fluids and wrote down what he noticed about how they behaved. He said that the viscosity of an ideal liquid can be changed only by changing the liquid's temperature. If a liquid is heated, it tends to become less viscous (it flows better); and if cooled, it tends to be more viscous (it flows more slowly). Liquids that pour and behave like water, oil, and rubbing alcohol are called Newtonian fluids because they behave like the liquids Newton wrote about. If a Newtonian fluid stays at one temperature, its viscosity will stay the same.

But some liquids don't follow Newton's model of viscosity. These are called Non-Newtonian fluids. Their viscosity can be affected by things other than temperature. One thing that affects the viscosity of Non-Newtonian fluids is the application of shear stress. Examples of shear stress are squeezing, stirring, and pushing on or smacking the surface of the fluid. Any of these things can greatly affect the viscosity of a Non-Newtonian fluid.

There are two basic behaviors of Non-Newtonian fluids. One type of behavior is called shear thinning. Shear thinning fluids decrease in viscosity when a shear force is applied. That means they flow better. An example of a shear thinning substance is ketchup. When ketchup won't come out of the bottle, what do you do? You smack the bottle. Smacking the bottle (or applying shear force) makes the ketchup move. It becomes less viscous and flows out of the bottle faster. Other shear thinning fluids include margarine, gelatin, mayonnaise, honey, mustard, shaving cream, and blood. Sometimes these liquids will return immediately to their "thicker" condition when you stop applying force to them; but others will take awhile before they return to their original state.

The other type of Non-Newtonian fluid does something called shear thickening. Shear thickening liquids increase in viscosity when a shear force is applied. One very important shear thickening fluid is synovial fluid. This is a fluid in the joints of your elbows and knees. Normally this liquid is not very viscous

Materials:
- One box of corn starch (16 oz.)
- Large mixing bowl
- Cookie sheet, square cake pan, or something similar
- Pitcher of water
- Spoon

What To Do:
Pour approximately 1/4 of the box of cornstarch into the mixing bowl and slowly add about 1/2 cup of water. Stir. Sometimes it is easier to mix the cornstarch and water with your bare hands -- of course, this only adds to the fun. Continue adding cornstarch and water in small amounts until you get a mixture that has the consistency of honey. It may take a little work to get the consistency just right, but you will eventually end up mixing one box of cornstarch with roughly 1 to 2 cups of water. Notice that the mixture gets thicker or more viscous as you add more cornstarchs. Pour the mixture onto the cookie sheet or cake pan. Notice its unusual consistency when you are pouring it into the pan. Stir it around with your finger, first slowly and then as fast as you can. Skim you finger across the top of the ooblech. What do you notice? Sink you entire hand into the ooblech and try to grab the fluid and pull it up. Try to roll the fluid between your palms to make a ball. You can even hold your hand flat over the top of the pan and slap the liquid glop as hard as you can. Most observers will run for cover, as you get ready to slap the liquid, fearing that it will splash everywhere. But all of the ooblech stays in the pan...hopefully. If your mixture inadvertently splatters everywhere, you will know to add more cornstarch. As you play with the ooblech, consider why the liquid behaves in this manner. What causes it to feel like something solid when you squeeze it, yet it flows like syrup as it drips off your finger?

WARNING:
Over time, the grains of cornstarch will separate from the water and form a solid clump at the bottom of the plastic storage bag. It is for this reason that you must not pour this mixture down the drain. It will clog the pipes and stop up the drain. Pour the mixture into a zipper-lock bag and dispose of it in the garbage.

How it works:
Your ooblech is made up of tiny, solid particles of cornstarch suspended in water. Chemists call this type of mixture a colloid. Colloids or colloidal suspensions are mixtures of solids and liquids in which the solid partcles remain suspended but do not disolve. Milk is one common example of a colloid. The milk soilds and fats do not disolve in the water (which makes up 90% of the contents of milk) but they do not separate out of the liqui

Polymer gels are made of long, thin, molecules such as protein or synthetic polymers cross-linked to form a random network that traps and holds liquids. When the microscopic gaps in the network are empty, the gel is shrunken and rigid. But when liquid creeps in, the gel swells and becomes softer and wobblier as the network loosens up.

Materials:
-diaper (large, disposable and super-absorbent)
-ziplock bag (1 gallon size)
-water
-small cup
-clear plastic cup
-paper towel
-food coloring
-dropper
-measuring spoons

WARNING:
The powder found in the diaper (sodium polyacrylate) will irritate the nasal membranes if inhaled. Avoid eye contact; if it gets into eyes, they will become dry and irritated. Be sure to wash hands after use.

What To Do:
Use a pair of scissors to cut off the paper or plastic edge around the entire diaper. Place the padded middle part of the diaper into the zip-closing plastic bag. Reach into the bag with both hands and separate the cotton, paper, and plastic layers of the diaper. Leave all material in the bag. Seal the bag and shake it for about 1 minute. Look at the bottom of the bag as you tilt it to one side. You should notice white granules collecting in the corner of the bag. Now, without opening the bag, move the cotton, plastic, or other large pieces of material toward the top of the bag. Keep the material up there as you shake the bag again. This will allow the granules to fall down to the bottom without getting picked up by the cotton again. After you have about teaspoon of granules in the corner of the bag, slowly open the bag and remove the large pieces of material. Throw them away. Now, carefully pour the granules into a small cup. Wash you hands.

Place about cup of water into a small cup. Add two or three drops of food coloring and swirl to mix. Place a small mount (about 1/8 teaspoon) of the powder onto the center of a paper towel. Add one drop of the colored water to the ranules on the paper towel. Continue adding one drop at a time to the granules and observe. What do the granules appear to be doing? How many drops can you add to the granules before the water spreads out much on the paper towel?

Take the rest of your granules and pour them into a clear plastic cup. Predict the number of tablespoons of water the granules can gel. Now try it by adding 1 tablespoon of water at a time. Watch what happens. What do you observe?How close was your prediction?

How it works:
The gel particles inside disposable diapers are made of sodium polyacrylate which is a man-made polymer. The sodium ions are the gel's secret weapon for luring water molecules inside its structure at a reasonably low temperature. The
polymer gel in a dry diaper only has about one percent water, so the particles are very small. When the diaper gets wet, water molecules

Materials:
-14 oz. can sweetened condensed milk
-1 Tbs cornstarch
-10 to 15 drops green food coloring

What To Do:
Pour the can of condensed milk into a saucepan. Add cornstarch and cook over low heat, stirring constantly. When the mixture thickens, remove from heat and add food coloring. Cool before using.