Download Unit 2 learning targets

Chemistry Unit 2, Week 1 Packet
Atomic Structure and Theory
Tuesday, October 1st – Friday, October 4th
MA Framework Standard
Check when met
2.1 Recognize discoveries from Dalton (atomic theory), Thomson (the electron),
Rutherford (the nucleus), and Bohr (planetary model of atom), and understand
how each discovery leads to modern theory.

2.2 Describe Rutherford’s “gold foil” experiment that led to the discovery of the
nuclear atom. Identify the major components (protons, neutrons, and electrons)
of the nuclear atom and explain how they interact.

2.3 Interpret and apply the laws of conservation of mass, constant composition
(definite proportions), and multiple proportions.

Weekly Homework Schedule
Tuesday 10/1
Early Models of the Atom Worksheet Questions
Page 4
Wednesday 10/2
Electrons Worksheet Questions
Page 8
Thursday 10/3
Section 1 Review Questions, Study for Quiz
Page 11
Friday 10/4
Complete Atomic Theory Graphic Organizer
Page 13
Reminder: Atomic Theory Quiz on Friday, October 4th
Atomic Theory Introduction: John Dalton’s Contributions
What is a model? Why do we use them in science?
Where did our model get us to today?
Atoms are made of __________________, ____________________, and _____________________.
Subatomic Particle
Charge
Mass
Location
Proton
Neutron
Electron
How did the model begin? John Dalton’s Atomic Theory of Matter/Solid Sphere Model
What he said
Law/Example; Still true today?
1. Each element is composed of small
particles called ________________. They
cannot be broken up into smaller particles.
2. All atoms of an element are identical in
mass and other properties; all atoms of
different elements are _________________.
3. Atoms cannot be ________________ or
Law of Conservation of Mass
__________________ in chemical
reactions. Before = after.
4. Compounds form when atoms of more
Law of Constant Composition
than one element combine. Specific
compounds always have the ___________
# of atoms and form in whole number ratios.
Law of Multiple Proportions
Practice MCAS Questions based on Dalton’s Laws
Law of Conservation of Mass
1. A balanced equation is shown here: C6H12O6(l)  2C2H5OH(l) + 2CO2(g)
Which of the following statements correctly compares the mass of the reactant with the mass of the products
in this equation?
A. The mass of the reactant is half the mass of the products.
B. The mass of the reactant is twice the mass of the products.
C. The mass of the reactant is one-fourth the mass of the products.
D. The mass of the reactant is the same as the mass of the products.
2. The equation below shows the chemical reaction that occurs in a car battery.
How much sulfuric acid (H2SO4) is consumed in the reaction?
A. 0.78 kg
B. 0.95 kg
C. 2.15 kg
D. 3.10 kg
Law of Constant Composition
3. A 1.00 kg sample of water (H2O) contains 0.11 kg of hydrogen (H) and 0.89 kg of oxygen (O). According to
the law of constant composition, how much hydrogen and oxygen would a 1.5 kg sample of water contain?
A. 0.11 kg H and 0.89 kg O
B. 0.17 kg H and 1.34 kg O
C. 0.22 kg H and 1.78 kg O
D. 1.34 kg H and 0.17 kg O
Law of Multiple Proportions
4. Which of the following statements applies the law of multiple proportions to the relationship between carbon
monoxide (CO) and carbon dioxide (CO2)?
A. The mass of a mole of CO is exactly half that of a mole of CO2.
B. There will always be half as much CO as CO2 in a sample of gas.
C. The proportion of oxygen atoms in CO molecules is the same as it is in CO2 molecules.
D. The mass of oxygen in CO compared to that in CO2 can be expressed as a whole number ratio.
Name
CHAPTER 4
Class
Date
Atoms
1 The Development of Atomic Theory
SECTION
KEY IDEAS
As you read this section, keep these questions in mind:
• What scientists helped to develop atomic theory?
• What part of atoms did Thomson discover?
• What part of atoms did Rutherford discover?
Who Proposed the First Atomic Theory?
You may know what atoms are: they are the tiny particles that make up all matter. Today, we know a great
deal about the structure and behavior of atoms. However,
scientists have not always known about atoms.
ORIGINS OF ATOMIC THEORY
The things we know about atoms today were
discovered by many scientists over a long period of time.
In fact, the first person to hypothesize that atoms exist
was Democritus. Democritus was a Greek philosopher
who lived in the fourth century BCE. He suggested that
everything in the universe was made of tiny, indivisible
units. He called these units atoms. The word atom comes
from the Greek word atomos. Atomos means “unable to
be cut or divided.”
Scientists Who Helped Develop Atomic Theory
Scientist
Contribution
Democritus
first proposed that the universe is made up of tiny,
indivisible units called atoms
Democritus made many observations of how matter
changes. He thought that the movements of atoms caused
the changes he observed. However, Democritus did not
have any evidence to show that his theory was correct.
Although some people agreed with Democritus’s theory,
others thought that different theories were correct.
As the science of chemistry was developing in the 1700s,
scientists began to focus on making careful measurements
in experiments. Therefore, scientists began to collect more
accurate and precise data about matter. Just as scientists
do today, scientists in the past used data to decide which
theories were most correct.
READING TOOLBOX
Compare After you read this
section, write a paragraph
or two comparing Dalton’s,
Thomson’s, and Rutherford’s
models of the atom.
READING CHECK
1. Identify Where does the
word atom come from?
READING CHECK
2. Explain What do you
think is the reason that
not everyone agreed with
Democritus’s theory?
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Interactive Reader
67
Atoms
Name
SECTION 1
Class
Date
The Development of Atomic Theory continued
How Did Dalton Contribute to Atomic Theory?
READING CHECK
3. Describe How was
Dalton’s theory different from
Democritus’s?
8g^i^XVa I]^c`^c\
4. Apply Concepts Carbon
makes up 27% of the mass
of carbon dioxide. How many
grams of carbon are there in
88 g of carbon dioxide?
In 1808, an English schoolteacher named John Dalton
proposed a different atomic theory. Like Democritus, Dalton
proposed that atoms could not be divided into smaller parts.
However, unlike Democritus, Dalton performed scientific
experiments to find data to support his theory.
Dalton’s experiments showed that atoms of different
elements could combine in certain ways to form
compounds. This is known as the “law of definite
proportions.”
The law of definite proportions states that a chemical compound always contains the same proportion of a
particular element. For example, in any sample of water,
hydrogen will make up 11% of the mass of the sample.
In other words, in 100 g of water, there will be 11 g of
hydrogen and 89 g of oxygen.
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)ZESPHFO
)ZESPHFOBUPN
0YZHFO
0YZHFOBUPN
For any sample of water, 11% of its mass is hydrogen and 89% is
oxygen. This suggests that hydrogen and oxygen atoms combine in
specific ratios to form water molecules.
READING CHECK
5. Explain Why did scientists
have to develop new atomic
theories that were different
from Dalton’s theory?
Some parts of Dalton’s atomic theory are still accepted
by scientists today. In fact, Dalton’s explanation of how
atoms combine to form substances is considered the foundation of modern atomic theory. However, as scientists
continued to carry out experiments, they made new observations that did not fit Dalton’s theory. New theories were
developed that better explained the new observations.
Scientists Who Helped Develop Atomic Theory
Scientist
Contribution
Democritus
first proposed that the universe is made up of tiny,
indivisible units called atoms
John Dalton
carried out scientific experiments that showed that atoms
exist
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Interactive Reader
68
Atoms
Bonus/Extension
Sample Data for Dalton’s Experiments
Experiment 1. 30 g of carbon are burned in the open
Experiment 2. 30 g of carbon are burned in a closed
air where there is plenty of oxygen. 110 g of carbon
container under conditions of low oxygen. 70 g of
oxide forms.
carbon oxide forms.
How much oxygen did the carbon combine with in
experiment 1? ___________________________
How much oxygen did the carbon combine with in
experiment 2? ___________________________
1. What is the ratio of the masses of carbon to oxygen in both experiments?
2. Is the ratio of masses an integer (whole #) or a number containing decimals (rational #)?
3. How might this data be explained according to Dalton?
Name
SECTION 1
Class
Date
The Development of Atomic Theory continued
How Did Thomson Contribute to Atomic
Theory?
In 1897, a British scientist named J. J. Thomson was
working with cathode rays, mysterious rays in vacuum
tubes. His experiments helped scientists better understand the structure of atoms.
In his experiments, Thomson used a vacuum tube
that contained two electrodes. One electrode, called the
cathode, was negatively charged. The other, called the
anode, was positively charged. When electricity was sent
through the tube, a glowing beam appeared inside the
tube. Other scientists had shown that this beam came
from the cathode. However, they had not been able to
determine what the beam was made of.
When Thomson placed a magnet near the tube, the
beam was deflected, or bent, as shown in the figure
below. Only streams of charged particles can be bent
by a magnet. Light rays cannot. Therefore, Thomson’s
experiment suggested that cathode rays were actually
streams of tiny, charged particles.
READING CHECK
6. Identify Which electrode
in Thomson’s vacuum tube
was positively charged?
The beam is
straight when no
magnet is present.
The cathode has a
negative charge.
The air was removed
from the tube by a
vacuum pump.
The anode has a
positive charge.
EHHDBG@<EHL>K
7. Explain Why did the
deflection of the beam
by a magnet suggest that
the cathode ray contained
charged particles?
The beam is deflected by the
magnet. Electric charges
behave in this way. So, the
deflection suggests that the
beam is made of charges.
Based on the direction the beam bent, Thomson
determined that the particles in the beam were
negatively charged. His experiments also showed that,
no matter what substance the cathode was made of,
the beam was always the same.
Based on his results, Thomson concluded that the particles in the beam came from atoms. He also concluded that
the particles were the same in atoms of different elements.
This is how Thomson discovered electrons, the negatively
charged particles inside an atom.
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69
Atoms
Thomson Discovers the Electron and Proposes the Plum Pudding Model
Scientist
JJ Thomson
Robert Milikan
Experiment/Notes
Cathode Ray Tube Experiment
Oil Drop Experiment
Name _______________________________________________________
Table Texting
Question:
My Response:
Reply 1:
Reply 2:
Reply 3:
EXPECTATIONS:
- Only share comments
related to the question
posed.
- Respectfully agree, disagree
or ask a follow up question in
your reply
- Be scholarly in your
response. Use background
knowledge and/or text clues
to support your ideas.
Bonus/Extension: Draw and explain the plum pudding model below. Propose an experiment that would
support or disprove Thompson’s model of a “pudding” of positive charge. Rutherford Discovers a Positive Nucleus and
the Nuclear Atomic Model
Video and Reading Notes
Name:
Date:
Rutherford’s Gold Foil Experiment
Background Info: In Rutherford’s experiment, he used radioactive
alpha particles. He directed these at a thin sheet of gold foil, shown in
the diagram to the right. He wanted to see if the particles would go
through the foil, or bounce back.
Before this experiment, scientists had two different possible ideas of
how atoms could be structured:
Plum Pudding Model:
In this model, the atom has negative particles (electrons) spread
out evenly through a positive sphere. If this is how an atom is
structured, all of the alpha particles should go straight through
since there is nothing solid to stop them.
Nuclear Model:
In this model, the negative electrons are on the outside, and there
is a small dense positive nucleus in the middle. If this is how an
atom is structured, alpha particles that enter the atom in the
electron areas will go straight through, which particles that hit the
nucleus will be bounced back.
Results: Rutherford’s experiment found that almost all of the alpha particles went straight through the
foil. A few bounced back and were deflected.
Question: Which model did Rutherford’s results support? Explain your answer.
Claim: Write a sentence that answers the question.
Evidence:
Most of the particles _________
__________________________
__________________________
Some of the particles ________
__________________________
__________________________
Analysis: Explain what each piece of evidence means about the
structure of the atom.
Name
Class
Date
Section 1 Review
SECTION VOCABULARY
electron a subatomic particle that has a negative
charge
nucleus in physical science, an atom’s central
region, which is made up of protons and
neutrons
1. Describe What did Rutherford’s gold-foil experiment suggest about the structure
of an atom?
2. Define State the law of definite proportions in your own words.
3. Compare How was Dalton’s atomic theory similar to Democritus’s atomic theory?
4. Compare How was Thomson’s atomic theory different from Rutherford’s atomic
theory?
5. Describe What did Thomson conclude about the particles in cathode rays?
6. Apply Concepts Nitrogen makes up 82% of the mass of ammonia. How many
grams of nitrogen are there in 200 g of ammonia?
7. Calculate The compound ammonia contains nitrogen and hydrogen atoms. How
many grams of hydrogen are there in 150 g of ammonia? (Hint: What percentage
of the mass of ammonia is hydrogen?)
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72
Atoms
Bohr Proposes the Solar System Model
What did Bohr find?
What did Bohr propose?
Models of the Atom Review
Scientist #1: Thompson
It is possible to remove a
negatively charged particle
from an atom using electrical
forces.
Does this evidence better support the solid sphere model, or the
plum pudding model? Explain your reasoning:
Scientist #2: Rutherford
Does this evidence better support the nuclear model or
If a tiny particle is shot into the middle of the plum pudding model? Explain your reasoning:
an atom, it hits something dense in the
center and bounces back in the
direction from which it came. If a tiny
particle is shot into the edges of the
atom, it goes through. Most of the
particles shot at an atom will go through.
Scientist #3: Bohr
The farther from the center of
an atom the negatively
charged particles are, the
easier they are to remove.
Does this evidence better support the solar system model or the
nuclear? Explain your reasoning:
1. Which scientist first showed that atoms are not just a solid sphere that can’t be divided?
2. What subatomic particle did JJ Thompson identify?
3. Which scientist figured out that atoms have a nucleus?
4. Which scientist showed that electrons are located at different distances from the nucleus?
Atomic Theory Graphic Organizer: How Did Models Get Us To Where We Are Today?
Scientist Name
1803
1897
1911
1913
Model Name, Key Points of Model
Solid Sphere Model
Plum Pudding Model
Nuclear Model Solar System Model