MATTER

LESSON 3- WHAT ARE ATOMS?

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AIMS: 

1.  What is an atom?

2.  What are some vocabulary words associated with atoms?

3.  What is the structure of an atom?

MOTIVATION:

Show students the following pictures:

[Image: Atom Description Graphic]

Ask the following questions:

a.  What are these pictures of?

b.  What can we compare their structure to?  (The planets in orbit).

c.  What force holds the planets orbit around the sun?  (Gravity).  What force do you think holds the particles in orbit in these pictures?  (Opposite electrical charges).

Have students log onto the following site to find out what an atom is: http://education.jlab.org/atomtour/  ( Atoms are the basic building blocks of matter that make up everyday objects.  A desk, the air, even you are made up of atoms!).

PROCEDURE:

    1.  Have students log onto http://education.jlab.org/atomtour/listofparticles.html,

http://science.howstuffworks.com/atom1.htm and http://chem4kids.com/files/atom_structure.html  and fill in the following database:

Click here for a blank student vocabulary database.

WORD DEFINITION
atom smallest piece of an element that keeps its chemical properties
proton particle in the nucleus of an atom with a positive charge
neutron particle in the nucleus of an atom with no charge
electron particle orbiting the nucleus of an atom with a negative charge
nucleus dense, central core of an atom (made of protons and neutrons)
orbit path an electron takes around the nucleus
shell A shell is sometimes called an orbital or energy level.
Shells are areas that surround the center of an atom.
 
molecule smallest piece of a compound that keeps its chemical properties (made of two or more atoms)
ion electrically charged atom (i.e., excess positive or negative charge
charge You can also see that each piece has either a "+", "-", or a "0". That symbol refers to its CHARGE. You know when you get a shock from a socket, static electricity, or lightning? Those are all different types of charges. Even in something as small as an atom there are charges.

    2.  Show students some models of the atom like the following: 

The planetary structure of the atom has the nucleus as the sun and electrons like planets[Image: Atom Description Graphic]

    3.  Identify the three basic parts of the atom: the nucleus (which contains the protons and neutrons), and the electrons (which orbit the nucleus).

    4.  Have children log on to the following websites to see examples of atomic structure and watch two BrainPop movies on the atom: http://brainpop.com/science/matter/atoms/index.weml  for the BrainPop movies and http://chem4kids.com/files/atom_structure.html which not only shows the atom's structure but explains the orbits, charges, shells, etc. 

    5.  Ask some questions based on the movies watched and the websites looked at:

            a.  What is the nucleus comprised of?

            b.  What charge does each particle carry?

            c.  What holds the electrons in orbit?

            d.  What makes each atom different from another one?

            e.  Can atoms share electrons?

ACTIVITIES:

1.  The following activity, which shows that atoms have positive and negative parts, and is quite simple, comes from Janice Van Cleave's Chemistry for Every Kid, John Wiley and Sons, Inc.

Paper Hop

Problem:  How can we show that atoms have positive and negative charges?

Hypothesis:  If we can rub some electrons off an item, and make it positively charged, then it will stick to an item of the opposite charge.

Materials:  piece of notebook paper, paper hole puncher, small balloon, clean hair

Procedure:  1.  Use the hole punch to cut about 15-20 small circles from the piece of paper.  2.  Spread the pieces on a table.  3.  Inflate the balloon and tie it.  4.  Rub the balloon against your hair about five strokes.  6.  Hold the balloon close to, but not touching, the paper circles.

Observations:  The paper circles jump to the balloon.

Conclusion:  Paper is an example of matter, and all matter is made up of atoms.  Each atom has a positive center with negatively charged electrons spinning around outside.  The balloon rubs the electrons off of the hair, giving the balloon an excess of negative charges.  The positive part of the paper circles is attracted to the excessive negative charge on the balloon.  This attraction between the positive and negative charge is great enough to overcome the force of gravity and the circles will hop upward toward the balloon.

2.  This next activity is  more advanced, but can be done in the classroom with supervision.  It is taken from Fizz, Bubble, and Flash, by Anita Brandolini, PhD., Williamson Publishing, Charlotte, Vermont.

Take a Water Break!

Problem:  How can we break a molecule of water  into its two elements, hydrogen and oxygen?

Hypothesis:  If we can get the hydrogen and oxygen atoms to attract to different charges, then we can show the two different atoms.

Materials:  ruler, 2, 6" to 8" pieces of insulated copper bell wire, 4 alligator clips, water, small glass or jar, two pencil "leads" (from a lead pencil), tape, and a 9-volt battery.

Procedure:  1.  Strip about 1/2" of insulation from both ends of the wire pieces and attach a clip to each end of both wires.  2.  Pit about 2" of water into the glass.  Place the pencil "leads" into the water, about 1" apart, and tape it to the sides of the jar above the water level.  Make sure the "leads are about and inch above the top of the glass. The "leads" are your electrodes.  3.  Clip one end of each wire to the top of a lead.  Attach the other ends of the wires to the battery terminals.  4.  Observe the water closely.

Observations:  We saw bubbles of gas forming along each lead.

Conclusion:  Water and carbon (the pencil "lead") both conduct electricity, providing a pathway along which it flows.  When the wires are connected to the battery, electrons travel around and around in a circle from the battery, along one wire,  through the lead, across the water, through the other lead and wire, and back into the battery.  As this electrical current passes through the water, it breaks water -H20- into its elements, hydrogen and oxygen.  The bubbles we saw were gases- hydrogen along one, oxygen along the other.  This simple process is called electrolysis.

FOLLOW UP: 

1.  Have children look at the Periodic Chart of the elements and find the atomic number and weight of five different atoms.

2.  Have them take the BrainPop quizzes on the Atom and the Atomic model.

3.  Have students log onto http://galaxy.net/~k12/matter/atoms.shtml and do the experiment there where they will create their own atom using everyday materials.

4.  Log onto http://education.jlab.org/atomtour/listofparticles.html and do an interactive lesson on the structure of the atom.

5.  Do the BrainPop activity at http://brainpop.com/science/matter/atomicmodel/activity.weml

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Developed by Bonnie Glasgold, TeachNet, 2004