# Atom Notes_2_

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Atom Notes
Let’s review!

What makes up everything we can touch and feel? The whole universe? ______________________

Matter is made of particles. When we heat something up, what happens to the particles?

When we cool something down, what happens to the particles?

Remember the food coloring in the water? The food coloring spreads faster in the hot water because the
molecules are moving faster. Although the particles in the water are too small to see, we can still see the
effect of their movement by the spreading of the food coloring. The faster the particles move, the faster

So what are these particles that all matter is made of? These particles are called _______________.
When two or more atoms combine together they form a____________________________________.
An atom is: _______________________________________________________________________.

How big are atoms?
1. Let’s do a demonstration with salt. How big are atoms?

2. Now let’s look at the piece of aluminum foil given to you by the teacher. What is the smallest particle of
matter within the piece aluminum? How small is each of the
___________ within the aluminum foil?

How many aluminum atoms stacked together would it take to equal the thickness of a piece of aluminum
foil.

3. Now take a look at the penny that was given to your group. The penny contains about how many
atoms?

Please open your book to page 87. Please look at figure 10 and describe in a few sentences how small
an atom is using the figure 10 as a helper.
Discovery of Atoms:

Democritus
One of the scientists to challenge the big question of matter, 2000 years ago.

1. What did Democritus discover?

What did he name his discovery?

Dalton
In 1803, John Dalton proposed the Atomic Theory. He performed a number of experiments that helped
him develop this theory. There are 4 parts to his Atomic Theory:
1.

2.

3.

4.

Thomson
In 1897, Thomson was studying what happened when he passed an electric current through a gas. The
gas gave off negatively charged particles even though the gas was uncharged (neutral). Where did they
come from?

1. What did Thomson discover?

2. What did Thomson’s model of the atom look like? We call it the chocolate chip cookie model.

Rutherford
In 1908, Ernest Rutherford was experimenting with shooting a stream of tiny positively charged particles
at a sheet of very thin gold foil. Most went straight through and some bounced off to the side or right back
at him as if they had hit something solid. Let’s draw a picture of his experiment:

1. What did Rutherford discover?

2. What did Rutherford’s model of the atom look like?

Bohr
In 1913, Niels Bohr proposed his “Planetary Model” of the atom. In this model, the electrons orbit around
the nucleus in different energy levels, similar to how planets orbit around the Sun.

1. What did Bohr’s model of the atom look like?
This is what we know about atoms:

1. The center of the atom is called the nucleus. It contains protons (+) and neutrons (no charge).
2. Orbiting around the outside of the nucleus are teeny, tiny electrons (-).
3. In order for an atom to remain neutral, the number of ___________________ must equal the
number of ________________________.
4. Most of the atom is made of __________________________________________.

What’s inside and Atom? :
For this section, please open your blue Matter text to page 88 and read pages 88-89 and answer the
following questions.

1. What smaller particles form the nucleus of the atom? Is the nucleus of an atom the same as a nucleus
of a cell? Explain Why or Why not.

2. Explain why atoms are neutral in charge.

3. Why do scientists say that most of the mass of an atom is located in the nucleus?

4. Draw a current model of the atom.

Let’s fill in the following chart
Atomic particle                          Location                                Charge

Positive (+)

Outside the nucleus

Neutron

5. Now that you know about how atoms relate to matter and how the parts of an atom relate to an atom,
on the back of this paper please use the following words below to design your own concept map. Your
concept map must include all of the words and clues that are 1-2 sentences used to connect each of the
words (concepts) of your map.

Words: Atom, Molecule, Compound, Property, Matter, Electron, Nucleus, Neutron, Proton, solid, liquid,
gas, phases of matter, structure, density, mass, volume, conductivity, solubility, malleability.

6. Now that you are all finished please get a laptop computer and explore the websites listed below in
order. Be sure to explore each one very carefully. You may need to remember info from each of the sites.
Model of an Atom:

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http://education.jlab.org/atomtour/index.html

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The Atom’s Family
http://www.miamisci.org/af/sln/credits/index.html

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Concept Map:

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