Judith A. Puglisi
Before presenting the historical overview students should read the following vocabulary from the board aloud. The vocabulary should be explained and discussed by the teacher. Students should than copy the vocabulary into their science journals. Tell students they should study the vocabulary for homework. They will be asked to explain the meanings of each word during the next class. I will start by telling students the definition and asking them to find the corresponding word. Mastering this vocabulary will most likely not take place in one day. Vocabulary review will take place the first ten minutes of every class. I ask for volunteers rather than call on students. I have no problems finding students to volunteer. Students become accustomed to daily vocabulary reviews and are interested in eventually mastering all the words. I emphasize the importance of becoming scientifically literate and informed citizens.
1. matter: anything that mass and volume.
2. element: simplest type of pure substance.
3. atoms: smallest particle of an element that has characteristic properties of that element.
4. alchemist: a chemist who lived during the middle ages, whose primary goal was to transform matter into gold. They often stressed secrecy rather than clarity. They are the forefathers of experimentation. They were the first to use what is known today as the scientific method.
5. pharmaceutical: of pharmacy or drugs.
6. by-products: anything produced in the course of making another thing.
7. philosopher: during the early 1800’s it meant “scientist”. Today it means a person who studies the principles underlying conduct, thought, and the nature of the universe. One who loves knowledge.
8. Indivisible: cannot be divide any further.
9. Theory: a formulation of underlying principles of certain observed phenomena which has been verified to some degree.
10. hypothesis: an unproved theory.
Ancient Greek Philosophers argued over what they believed to be the nature of matter. They believed the world was far more simple than it appeared. A philosopher named Leucippus theorized that all matter was essentially composed of one simple substance. In about 400BC another Greek philosopher, Democritus, named this simple substance “atoms”, which meant “uncuttable”. Their theory was that if matter was repeatedly cut into smaller and smaller pieces, it would eventually result into a piece that could no longer be cut. This theory about matter remained the same for hundreds of years. Scientific investigations into the behavior of matter began by a group of people called Alchemists who wished to transform everything imaginable into precious metals, such as gold and silver. They also tried to manipulate matter into potions that would allow people to live forever. These early scientists actually studied problems and created experiments to test their theories.(3)
Today’s scientists continue to investigate chemistry concepts in order to explain the many events we observe in our daily lives. Pharmaceutical companies continue to search for medicines to keep us living longer, cosmetic companies search for creams and potions to slow down or disguise the aging process in our bodies, and government agencies are working on new ways to recycle the by-products of human activities. Who would have guessed that such a simple concept as “all matter can be broken down into a single indivisible substance called the atom”, would have opened the doors for such complicated research and discoveries that we see today.
After introducing the historical overview, students will view the Nova video Kaboom. This video shows modern day scientists replicating experiments from the journals of ancient alchemists.
At this point before starting your content teaching, be prepared to assign research topics to higher level students. Develop a list of important scientists in the field of chemistry for the student to choose from. Your list may include the following scientists: Priestley, Lavoisier, Boyle, Liebig, Dalton, Newton, Mendelelyev, Avogadro, Berzelius, Boltzmann, Mamma Curie, C.W. Leadbeater, and Pasteur. Make it clear to these students that they are to work on their independent research when ever they finish their assigned class work. Bright students can turn into behavior problems when allowed to become bored in class. I usually collect related books to keep in my classroom. My school librarian has also developed lists of related books available in our school library for use by my students. It is an extremely open ended assignment. Students are asked to give a class presentation upon completion of their research. Some students spend long periods of time on visual aids. Other students produce long narratives. If the student needs assistance with their presentation I allow other students to help. For instance a poor reader may have a student reads certain parts of their research during their presentation. I have also acted as an assistant to extremely shy students. Any interested student can participate. I also help the students to find related educational videos and classroom speakers to help stimulate interested in the particular topic presented. Students always take great pride in their independent research projects. I have never had a student who has not wanted to present his of her work to the class. If all the students become interested in this project it may be wise to break the class into research teams.
11. inertia: the property of a material that resists any change in its state of rest or motion.
12. density: the scientific way of comparing the “heaviness” of materials. It is the measurement of the mass of a specified volume.
13. physical property: characteristic that distinguishes one type of matter from another and can be observed without changing the identity of the substance.
14. chemical property: property that describes how a substance changes into a new substance.
15. gravity: the force that pulls objects on the earth toward the center of the earth. The pull of gravity on an object determines the object’s weight.
Matter is the substance that all things are made of. Everything you see around you is made of matter. It may have very different physical and chemical properties, but all matter takes up space and has inertia and mass.
Mass is the amount of matter in a given object. Mass does not change. The mass of a person is the same on the earth or the moon. The weight of that same person will change due to the change in the gravitation pull of each planet. The amount of mass in an object is constant. Weight is not a constant. Although an object in space is said to be weightless, it is not massless.
Mass is a measure of the inertia of an object. Inertia is the resistance of an object to changes in its motion. Objects at rest need force to move them. Objects in motion need force to stop or change movement. A marble resting on a desktop will not move until a force, such as your hand, is used to move it. That same marble in motion will need a force to stop it from rolling down a ramp. If we replace the marble with a bowling ball it will require more force to start or stop its motion, than was required for the marble. The more mass an object has the greater its inertia.
Matter takes up space. The amount of space an object takes up is called its volume. Liter, milliliter, and cubic centimeter are the metric units used to express volume. In general, liters and milliliters are used to measure liquids and cubic centimeters are used to measure the volume of solids.
Density is the mass per unit volume of an object. All matter has density. The density of a specific kind of matter is the property that helps to identify it and distinguish it from other kinds of matter. Density of an object is the amount of matter in a given amount of space or volume.
To demonstrate the different densities of liquids.
Materials: 1 tall, clear container, 1 grape, 1 cork, I plastic building block, water, cooking oil, and syrup.
Procedure: *Pour the syrup into the container
*Slowly pour in the same amount of oil. It floats on the syrup.
*Add the same amount of cold water. It sinks through the oil but floats on the syrup.
*Put the cork, plastic block, and the grape in the container.
*The objects float at different levels because they have different densities.(4)
Matter can exist in four phases: solid, liquid, gas and plasma. The plasma phase is extremely rare on Earth. The particles of any substance are constantly in motion. The type and extent of the motion determines whether the substance is a solid, liquid, or gas. Matter in the solid phase has less energy than matter in the liquid phase. Matter in the liquid phase has less energy than matter in the gas stage. When we add heat energy to liquid matter it will change to gaseous matter. When we take heat energy away from gaseous matter it will turn into liquid matter. If we continue to take more energy away the liquid matter will turn into solid matter.
To demonstrate the three phases of matter.
Materials: hot plate, sauce pan or other heat resistant container, two trays of ice cubes, and a large shallow baking pan .
Procedure: *Place ice cubes from one ice tray in sauce pan over hot plate.
*Place ice cubes from second tray in baking pan.
*As water in pan begins to boil place pan with ice above the boiling water.
*Heat from the hot plate will change the solid ice into water vapor, which will condense back into a liquid when it hits the cold, iced pan.
Solids have a definite shape. Their molecules are packed close together. Solids do not flow or move far apart. Solids can only vibrate. The internal structure of a solid is arranged in a regular, repeating pattern called a crystal. These solids are called crystalline solids. Amorphous solids are solids that lose their shape under certain conditions such as candle wax, or tar used to repair roads.
Liquid particles are close together but not as close together as particles in the solid stage. Liquid particles are free to move from one place to another, but the forces of attraction keep the particles close together. Liquids do not have a definite shape but they do have a definite volume.
The gas phase does not have a definite shape or volume. A gas fills all the available space of the container. Particles of a gas can be pushed close together as well as spread far apart. If allowed to gases will expand without limit. The gravitational pull of our planet holds our atmosphere close to the surface of the planet. Without this gravitational force holding the atmosphere, the gases would spread throughout the Universe.
Gas molecules are in constant motion. They move around at high speeds constantly hitting one another and the sides of their container. The more heat you add to the gas molecules the faster they will move, and spread apart. (5)
To demonstrate the expansion of gas molecules when heated.
Materials: 1 large empty metal olive oil container cleaned thoroughly, enough water
to fill ½ inch of the bottom of container, hot plate, the screw-on top to the
container, Oven mitt.
Procedure: *Fill water to fill ½ inch of the bottom of the container.
*Once you hear the water begin to boil, turn off the heating element.
*Using the oven mitt, place the top on the oil container and secure it
tightly. If the plastic seal on the spout breaks or cracks due to the
pressure from the water vapor, it will necessary to start over with a
new oil container.
Results: Within 5 minutes the can should begin to crush. The expanding water
vapor has pushed all the air out of the can. As the temperature inside
the can begins to cool, the water vapor condenses back into water. A
vacuum is formed. (6)
Behavior of Water Molecules
Water is one of the few compounds on Earth that can be naturally found in all three states. A major difference between each of these states is density, or how closely the water molecules are packed together in a given area. Water vapor is the least dense because of the large space between the molecules.
Heating and cooling water affect the density of water. Heating water speeds up the movement of water molecules. When the movement is increased the molecules are less likely to stay close together. Therefore warm water is less dense than cold water.
To demonstrate that warm water is less dense than cold water.
Materials: Large glass tank or bowl, Small bottle with cap, water, ink or food
Procedure: *Pour cold water into the tank until it is about three quarters full.
*Fill the bottle with hot tap water. Add a few drops of coloring.
*Screw the cap back on the bottle and shake it well.
*Place the bottle on the bottom of the tank and unscrew the cap.
*The hat water from the bottle is lighter, or less “dense,” than the cold water, so it shoots to the top of the tank.
*The hot colored water forms a layer on top of the cold water. As it cools, the colored water mixes with the cold water.(7)
If cold water is denser or heavier than warm water than how does an even colder water called “ice” float in water? Give each group of two students a container of water and two ice cubes. Ask students to observe these two phases of water and hypothesize as to why the ice floats in liquid water. They should write their ideas in their science journal and diagram the floating ice.
Draw a diagram on the board of a water molecule. Diagram molecules as you might think they would look like as a liquid. Spread them even further apart to represent a gas. Ask the students to guess how they think the molecules would look when the water is frozen. Students will build their own water molecules to represent the solid phase “ice”.
Materials: 8 red gum drops, 4 yellow gum drops and 12 tooth picks per student, student science journal.
Procedures: *Each student must create 4 water molecules out of gum drops.
*The student must represent each phase of water using their models.
*The student will draw pictures of the molecules representing each phase of water in science journal.
*The model representing “ice” must use more room than liquid water, but less room than water vapor.
*The student must develop a hypothesis as to why ice floats in water.
Results: Water expands when it freezes. In ice, water molecules are actually further
apart from each other. Hydrogen bonds easily form when water molecules
have little heat energy and are moving slowly. The strong hydrogen bonds
force water molecules into a lattice pattern, holding them apart from each