1. 4.1 Studying Atoms
Wrap: 1/22/2013 Pg 102-110
1. What are the major ideas in Democritus theory(2)?
2. What are the major ideas in Aristotle’s(2)? Who’s
theory is closer to our modern understanding of matter?
3. What does Dalton’s atomic theory state (3 parts)?
What part do you know is wrong?
Try:
Balance: Al2O3+ MgS Al2S3 + MgO

2. 4.1 Studying Atoms
Wrap: 1/24/2012 Pg 106-119
1. What is an atom? Compare the number of atoms in a
penny to the number of people in the world.
2. Why was Rutherford important? Draw his model of the
atom
3. How is atomic number different than atomic mass. What
is the atomic # and mass of V and Sg?
4. Give 2 facts each about protons, neutrons, and
electrons.
How many p,n,e’s are in Tungsten?

3. 4.1 Studying Atoms
Atomic Theory
Contributions / Experiment used/
Theory Explain Model
Aristotle Believed everything was
made of fire, air, water
DO NOT DO!!
and earth
Democritus Believed everything
was made of atoms
DO NOT DO!!
Dalton (Know 3 parts) DO NOT DO!!
Thomson Discovered the
electron and size of
Used cathode ray tube-
particles were attracted to
electron positive end of magnet
Rutherford Discovered nucleus,
and overall charge and
Gold foil experiment-some
alpha particles bounced straigh
volume of nucleus back. Most went through

4. 4.1 Studying Atoms
Elements to know by Friday
Flash Cards?
• First 20 elements name and chemical symbol
(H- Ca) (For Friday). Also Atomic Theory
• Also Cr, Fe, Ni, Cu, Zn, Br, I, Sr, Zr, Ag, Cd,
Sn, Sb, Xe, Rn, Cs, Ba, Pt, Au, Hg, Pb, W, Fr,
Ra, U, Pu (For Monday)

5. 4.1 Studying Atoms
Wrap: 8/24/2011 Pg 102-114
1. Who discovered the nucleus? How? Why did he
conclude the nucleus had an overall + charge?
2. Explain how Thomson knew the particles inside the
cathode rays were negative.
3. How does the volume of the nucleus compare to the
volume of the atom?
4. Write out the actual mass of a proton, neutron and
electron( Convert from Sci Not). How does the mass of
a proton compare to the mass of an electron? Neutron?

6. 4.1 Studying Atoms
Wrap: 8/24/2011 Pg 102-114
1. Give 2 facts about Dalton, Rutherford, and Thomson. How
was Democritus theory different than Aristotle’s?
2. Define 4 vocab terms.
3. Read pg 114. Give 2 facts about each paragragh
STUDY!!! Reminder quiz over first 20 elements Friday, quiz over
elements given in class Monday.

7. 4.1 Studying Atoms
Wrap: 8/26/2011 Pg 115-121
1. What is the difference between atomic number, atomic mass
and mass number? What is Tin’s atomic number and mass?
2. How do you calculate the number of protons, neutrons, and
electrons? Calculate the p, n, e’s of Francium.
3. What is an isotope? Give an ex. How is C-12 different than
C-14?
4. How many p,n,e’s does Ag-110 have?

8. 4.1 Studying Atoms
Rap: 1/19/2011 pg: 67-74
1. How was Democritus theory different than Aristotle’s?
2. What does the law of conservation of mass state?
3. What does Dalton’s atomic theory state? What part do
you know is wrong?
4. Give 2 important concepts of the modern atomic theory.
5. Who discovered the electron? What was his model
called? Why do you think this model is incorrect
6. Give 3 reasons why it is a bad idea to misbehave for the
sub. If you were to apologize for your/your classes
behavior to the sub and Mrs. Sleep what would you say?

9. 4.1 Studying Atoms
Rap: 1/19/2011 pg 72-76
NO TALKING
1. Who discovered the nucleus? How? Why did he
conclude the nucleus had an overall + charge?
2. Explain how Thomson knew the particles inside the
cathode rays were negative.
3. How does the volume of the nucleus compare to the
volume of the atom?
4. What is located inside the nucleus? Why does it not
split apart?
5. What did you learn Yesterday about being bad for a
sub when Mr. Campbell is Absent?

10. 4.1 Studying Atoms
RAP: 1/21/2011 Pg: 67-75
1. Give 2 facts about Dalton, Rutherford, and Thomson
2. What is the difference between the law of definite
proportion and law of multiple proportions?
2H2 + O2  2 H2O
3. If you have 10g of hydrogen and you add it to 4g of
Oxygen how much H2O would you have? What law
does this demonstrate?

11. 4.1 Studying Atoms Section 1 The Atom: From
Chapter 3 Philosophical Idea to Scientific Theory
Foundations of Atoms
• Law of definite proportions: a chemical compound
contains the same elements in exactly the same
proportions by mass regardless of the size of the
sample or source of the compound
• Law of multiple proportions: if two or more different
compounds are composed of the same two elements,
then the ratio of the masses of the second element
combined with a certain mass of the first element is
always a ratio of small whole numbers

12. 4.1 Studying Atoms Section 1 The Atom: From
Chapter 3 Philosophical Idea to Scientific Theory
Law of Multiple Proportions

13. 4.1 Studying Atoms
Studying the structure of
atoms is a little like studying
wind. Because you cannot see
air, you must use indirect
evidence to tell the direction of
the wind. Atoms pose a similar
problem because they are
extremely small. Even with a
microscope, scientists cannot
see the structure of an atom.

14. 4.1 Studying Atoms
Ancient Greek Models of Atoms
The philosopher Democritus believed that
all matter consisted of extremely small
particles that could not be divided. He
called these particles atoms from the
Greek word atomos, which means
“uncut” or “indivisible.”

15. 4.1 Studying Atoms
Ancient Greek Models of Atoms
Aristotle thought that all
substances were made of only four
elements—earth, air, fire, and
water. He did not think there was a
limit to the division of matter.
For many centuries, most people
accepted Aristotle’s views on the
structure of matter. By the 1800s,
scientists had enough
experimental data to support an
atomic model.

16. 4.1 Studying Atoms
Dalton’s Atomic Theory
When magnesium burns, it
combines with oxygen. In
magnesium oxide, the ratio of
the mass of magnesium to
the mass of oxygen is always
about 3 : 2. Magnesium
dioxide has a fixed
composition.
What happens if you put
water on burning Mg?

17. 4.1 Studying Atoms
Magnesium burning
• http://www.youtube.com/watch?v=qrjYb1Oy-P

18. 4.1 Studying Atoms
Dalton’s Atomic Theory
Dalton’s Theory
• All elements are composed of atoms.
• All atoms of the same element have the
same mass, and atoms of different
elements have different masses.
• Compounds contain atoms of more than
one element.
• In a particular compound, atoms of
• different elements always combine in the
same way.

19. 4.1 Studying Atoms
Thomson’s Model of the Atom
When some materials are rubbed, they gain
the ability to attract or repel other materials.
Such materials are said to have either a
positive or a negative electric charge.
• Objects with like charges repel, or push apart.
• Objects with opposite charges attract, or pull
together.

20. 4.1 Studying Atoms
Thomson’s Model of the Atom
Thomson’s Experiments
In his experiments, Joseph John Thomson
used a sealed tube containing a very small
amount of gas.
Sealed tube
Glowing beam Positive plate
filled with gas at
low pressure
Metal disk Negative plate
Metal disk Source of Metal disk Source of
electric current electric current

21. 4.1 Studying Atoms
Thomson’s Model of the Atom
When the current was turned on, the disks
became charged, and a glowing beam
appeared in the tube.
• Thomson hypothesized that the beam was a
stream of charged particles that interacted with
the air in the tube and caused the air to glow.
• Thomson observed that the beam was repelled
by the negatively charged plate and attracted
by the positively charged plate.

22. 4.1 Studying Atoms
Thomson’s Model of the Atom
Evidence for Subatomic Particles
Thomson concluded that the particles in the
beam had a negative charge because they
were attracted to the positive plate. He
hypothesized that the particles came from
inside atoms because
• no matter what metal Thomson used for the
disk, the particles produced were identical.
• the particles had about 1/2000 the mass of a
hydrogen atom, the lightest atom.

23. 4.1 Studying Atoms
• http://www.youtube.com/watch?v=O9Goyscba

24. 4.1 Studying Atoms
Thomson’s Model of the Atom
Thomson’s model is called the
“plum pudding” model. Today, it
might be called the “chocolate
chip ice cream” model.
The chips represent negatively
charged particles, which are
spread evenly through a mass of
positively charged matter—the
vanilla ice cream.

25. 4.1 Studying Atoms
Rutherford’s Atomic Theory
What contributions did Rutherford make to
the development of atomic theory?
According to Rutherford’s model, all of an
atom’s positive charge is concentrated in its
nucleus.

26. 4.1 Studying Atoms
Rutherford’s Atomic Theory
Rutherford’s Hypothesis
Ernest Rutherford designed an experiment to find out
what happens to alpha particles when they pass
through a thin sheet of gold. Alpha particles are fast-
moving, positively charged particles.
• Based on Thomson’s model, Rutherford hypothesized
that the mass and charge at any location in the gold
would be too small to change the path of an alpha
particle.
• He predicted that most particles would travel in a straight
path from their source to a screen that lit up when struck.

27. 4.1 Studying Atoms
Rutherford’s Atomic Theory
Alpha particles
The Gold Foil Experiment
Undeflected
Deflected
particle
particle
Gold atoms
Slit
Beam of alpha
particles Alpha particles
Screen
Source of
alpha particles
Nucleus

28. 4.1 Studying Atoms
• http://www.youtube.com/watch?v=5pZj0u_XM

29. 4.1 Studying Atoms
Rutherford’s Atomic Theory
Discovery of the Nucleus
The alpha particles whose paths were
deflected must have come close to
another charged object. The closer
they came, the greater the deflection.
However, many alpha particles passed
through the gold without being
deflected. These particles did not pass
close to a charged object.

30. 4.1 Studying Atoms
Rutherford’s Atomic Theory
Thomson’s model did not explain all of the
evidence from Rutherford's experiment.
Rutherford proposed a new model.
• The positive charge of an atom is not evenly
spread throughout the atom.
• Positive charge is concentrated in a very
small, central area.
• The nucleus of the atom is a dense,
positively charged mass located in the center
of the atom.

31. 4.1 Studying Atoms
• http://www.youtube.com/watch?v=L2KmCTst2

32. 4.1 Studying Atoms
Rutherford’s Atomic Theory
The Houston Astrodome
occupies more than nine
acres and seats 60,000
people. If the stadium
were a model for an atom,
a marble could represent
its nucleus.
The total volume of an
atom is about a trillion
(1012) times the volume of
its nucleus.

33. 4.1 Studying Atoms
Assessment Questions
1. Dalton’s theory did not include which of the
following points?
a. All elements are composed of atoms.
b. Most of an atom’s mass is in its nucleus.
c. Compounds contain atoms of more than one element.
d. In a specific compound, atoms of different elements
always combine in the same way.

34. 4.1 Studying Atoms
Assessment Questions
1. Dalton’s theory did not include which of the
following points?
a. All elements are composed of atoms.
b. Most of an atom’s mass is in its nucleus.
c. Compounds contain atoms of more than one element.
d. In a specific compound, atoms of different elements
always combine in the same way.
ANS: B

35. 4.1 Studying Atoms
Assessment Questions
2. J. J. Thomson’s experiments provided the first
evidence of
a. atoms.
b. a nucleus.
c. subatomic particles.
d. elements.

36. 4.1 Studying Atoms
Assessment Questions
2. J. J. Thomson’s experiments provided the first
evidence of
a. atoms.
b. a nucleus.
c. subatomic particles.
d. elements.
ANS: C

37. 4.1 Studying Atoms
Assessment Questions
1. The concept of an atom as a small particle of
matter that cannot be divided was proposed by
the ancient Greek philosopher, Democritus.
True
False

38. 4.1 Studying Atoms
Assessment Questions
1. The concept of an atom as a small particle of
matter that cannot be divided was proposed by
the ancient Greek philosopher, Democritus.
True
False
ANS: T

39. 4.1 Studying Atoms
Notes:
• Dalton proposed the theory that all matter is made up of
individual particles called atoms, which cannot be divided.
• An atom is neutrally charged unless the atom has lost or
gained electrons
• Rutherford found that when he shot a beam of alpha
particles (+) through gold foil some bounced back while
some went through
• According to Rutherford’s model, all of an atom’s positive
charge is concentrated in its nucleus.
• The nucleus of the atom is a dense, positively charged
mass located in the center of the atom.

40. 4.1 Studying Atoms
Notes:
• Dalton proposed the theory that all matter is made up of
individual particles called atoms, which cannot be divided.
• An atom is neutrally charged unless the atom has
lost or gained electrons
• According to Rutherford’s model, all of an atom’s
positive charge is concentrated in its nucleus.
• The nucleus of the atom is a dense, positively
charged mass located in the center of the atom.

41. 4.1 Studying Atoms
Elements to know by Friday
Flash Cards?
• First 20 elements name and chemical symbol
(H- Ca) (For Friday). Also Atomic Theory
• Also Cr, Fe, Ni, Cu, Zn, Br, I, Sr, Zr, Ag, Cd,
Sn, Sb, Xe, Rn, Cs, Ba, Pt, Au, Hg, Pb, W, Fr,
Ra, U, Pu (For Monday)

42. 4.1 Studying Atoms
Quiz Tomorrow
• Quiz will be over Chapter 3 sec 1+2
• Look over openers from yesterday and
Today.
• Look over notes from Today.
• Make sure you know the table we just did
• Quiz will be 10-15 Q’s long