Download Unit 04 Introduction to Atomic Theory

HHMenezes, Unit 4
Unit 04:
Introductory Atomic Theory
Author:
J. Galinski, S. Michalek, S. Menezes
Introductory Resources:
Addison-Wesley v.5 - Chapter 5
Addison-Wesley v.4 - Chapter 4
Addison-Wesley v.3 - Chapter 4
Main Idea Summary:
Elements are composed of atoms, which are the basic building blocks of matter.
The atoms of a given element are different from the atoms of all other elements.
Atoms contain positively charged protons, negatively charged electrons, and electrically
neutral neutrons.
The nucleus of an atom is composed of protons and neutrons. The electrons surround the
nucleus and occupy most of the volume of the atom.
The number of protons in an atom’s nucleus is the atomic number of that element.
Because atoms are electrically neutral, an atom has the same number of protons and
electrons.
The sum of the number of protons and number of neutrons is the mass number of an atom.
Atoms with the same number of protons but different numbers of neutrons are called
isotopes.
The atomic mass of an element is expressed in atomic mass units (amu).
The atomic mass of an element is a weighted average of all the naturally occurring isotopes
of that element.
In the periodic table, the elements are organized into groups (vertical columns) and periods
(horizontal rows) in order of increasing atomic number.
Elements that have similar chemical properties are in the same group.
Elements in the periodic table are classified as metals, nonmetals, or metalloids.
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HHMenezes, Unit 4
Unit 04 Introduction Atomic Theory
Outline
NAME: ______________________
4.1 Atoms
Dalton’s Atomic Theory
1.
2.
3.
4.
Atom
4.2 Electrons, Protons, and Neutron
Electrons
Cathode Ray Tube
Proton
Neutron
Particle
Symbol
Relative
Charge
AMU
Actual
Mass
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HHMenezes, Unit 4
4.3 The structure of the Nuclear Atom
Nucleus
4.4 Atomic Number
Atomic Number
4.5 Mass Number
Mass Number
4.6 Isotopes of Elements
Isotopes
4.7 Atomic Mass
Atomic Mass Number
Atomic Mass
4.8 Calculating the Atomic Mass of an Element
What are the three things you need to find the average atomic mass?
1.
2.
3.
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Discussion Sheet 4a – Early Atomic Theory
Scientist
Dalton
1808
Thomson
1897
NAME: ______________________
Relevant Experiments and Contributions to
Atomic Theory
Studied ratios in which elements combine in chemical
reactions:
 All elements are composed of tiny, indivisible
particles called atoms.
 All atoms of element X are identical. All atoms of
element X are different than atoms of any other
element.
 Atoms can chemically combine together in whole
number ratios.
 Chemical reactions occur when atoms are separated,
joined, or rearranged. Atoms of one element are
never changed into atoms of another element.
Passed electric current through gases at low pressure
using a cathode ray tube:
 Used a positively charged plate to demonstrate that
atoms contain negatively charged subatomic
particles called electrons.
 Electrons are extremely small. One electron is
about 1/2000 the mass of a hydrogen atom.
 Model called the “plum-pudding” model, named after
the British cuisine, with negatively charged
electrons floating in a positively charged “broth.”
Rutherford Directed a beam of alpha particles at a thin sheet of
gold foil:
1911
 Demonstrated that the atom is mostly empty space,
with a very dense core called a nucleus.
 Nucleus of atom is composed of positively charged
particles called protons.
 Protons are large subatomic particles. One proton
is equal to one atomic mass unit.
 The space between the nucleus and orbiting
electrons is completely empty.
Atomic Model
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4.01 – Early Atomic Theory
NAME: ______________________
1. With which of these statements would John Dalton have agreed in the early 1800s?
a.
b.
c.
d.
Atoms are the smallest particles of matter.
The mass of an iron atom is different from the mass of a copper atom.
Every atom of silver is identical to every other atom of silver.
A compound is composed of atoms of two or more different elements.
2. What experimental evidence did Thomson have for each statement?
a. Electrons have a negative charge. _____________________________________
b. Atoms of all elements contain electrons. ________________________________
3. Would you expect two electrons to attract or repel each other? Why?
4. How did the results of Rutherford’s gold foil experiment differ from his expectations?
5. What is the charge, positive or negative, of the nucleus of every atom?
6. Why is an atom electrically neutral?
7. What technology was available to Thomson in 1897 that was not available to Dalton in 1808?
8. What contribution did Millikan make to the development of atomic theory? Explain.
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Discussion Sheet 4b – Using the Periodic
In 1932, James Chadwick confirmed the existence of
particle: the neutron. Neutrons are subatomic
charge but with a mass nearly equal to that of a
fundamental building blocks of atoms are the
proton, and the neutron.
NAME: ______________________
Table
another subatomic
particles with no
proton. Thus, the
electron, the
Protons and neutrons are large, and found in the
nucleus, at the
center of the atom. The sum of the number of
protons and
neutrons in an atom is called the mass number. Protons are positively charged. Neutrons are electrically neutral. On
the other hand, electrons are negative. Electrons are very small, and are found far away from the nucleus.
The periodic table is an arrangement of all of the elements in the universe. The first periodic table was devised in
the 1800s by a Russian chemist named Dimitri Mendeleev. He organized all of the known elements based on what
atomic mass each one had. The elements in the modern table are organized according to their atomic number. There
are always two numbers in every entry in the periodic table: the atomic number and the atomic mass.
The atomic number is the number of protons in an atom’s nucleus. In a neutral atom, it is also the number of
electrons. The number of protons an atom has determines what type of atom it is. Every atomic number also
corresponds with an atomic symbol. If an element has an atomic number of 2, each atom of that element has 2
protons, and it can then be identified with the symbol “He,” which stands for helium. A helium atom may not have
more or less than 2 protons. The atomic number is always the smallest number in any periodic table entry.
The protons and neutrons are the heavier subatomic particles found in the nucleus of an atom. The mass number is
the sum of the number of protons and the number of neutrons in an atom. The atomic mass number is always the
largest number in any periodic table entry.
If you know the atomic number and mass number of an atom of any element, you can determine the atom’s composition.
The atomic number is equal to the number of protons and the number of electrons. The number of neutrons can be
determined from the following equation:
number of neutrons = mass number − atomic number
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HHMenezes, Unit 4
Atomic Structure Note Taking
Identify the parts of the picture:
A._______________________________________
_
B._______________________________________
C._______________________________________
D._______________________________________
Protons
Mass
Charge
Location
What does
it tell you
about an
element?
How can
you tell
how many
an element
has?
Atoms
are made of
Neutrons
Electrons
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
NAME: ______________________
SWS 4.01 – First 20
First 20 elements of the Periodic Table
Use the Periodic Table to fill in the following information.
Element
Symbo
l
Atomic
Number
Atomic Mass
(round to a
whole
number)
Number
of Protons
Number
of
Neutrons
Number
of
Electrons
Hydrogen
He
3
9
5
6
7
8
9
20
11
Mg
Aluminum
Si
15
32
17
22
19
Calcium
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4.02 – Atomic Composition
NAME: ______________________
Atomic Number
(# of Protons) = (# of Electrons)
Mass Number
(# of Protons) + (# of Neutrons)
Isotopes
same # of protons, but different # of
neutrons
1. Fill in the following table. The first entry has been done for you. (For the purposes of this
worksheet, you may round the number of neutrons to the nearest whole number.)
Element
Symbol
Atomic
Number
Lithium
Li
3
Mass
Number
Number
of
Protons
Number
of
Neutrons
Number
of
Electrons
7
3
4
3
Calcium
Sodium
Lead
Oxygen
Radon
Fluorine
2. What is the difference between the terms “atomic mass” and “mass number”?
3. Why aren’t all of the atomic mass numbers in the periodic table whole numbers? (Hint: It is not possible for an
atom to have a fractional part of a neutron.)
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HHMenezes, Unit 4
Lab Report Outline

General
o Put your name (first) and the names of your group members on the top of the
paper
o All labs must be typed for any credit.
o Please leave a space between each heading

Purpose/Question
o What is your objective

Background
o Brief background on experiment included in introduction
Materials
o List what you have used


Hypothesis
o If……………..then…………….because
o Must be done before lab.

Experimental Design
o Step by step no paragraph form
o Calculations are not to be done in the procedure
 Example
 Subtract the weight of the beaker from the weight of the sand and
beaker. (Data Analysis)

Data
o Record all data taken in lab and observations
 Qualitative
 Before, During and After Reaction
 Quantitative
 Must have correct units on all your data
 Use a chart or table
 Noticed Error
 Only if you need this section because you can see and evident error
Data Analysis
o Math equations

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HHMenezes, Unit 4
 Show work
 Final answer with units
o Qualitative Observations
 Reasons why observations happened. You may need to get online for this.

Conclusion
o Paragraph 1
 Restate problem
 Restate hypothesis
 Clearly state if you reject or accept your hypothesis
 Give evidence to why you do so using your data
o Paragraph 2
 State scientific principle
 What principle are we studying in this lab
 How do they pertain to the lab
o Paragraph 3
 State any possible problems
 There are always problems even if you don’t think there are
o Scale was off, didn’t weigh right amount, you spilled some of
you product
 Tell me the problem and how it has or could have affected your data
o Paragraph 4
 Pose a new question
 Inquire into science here
 What other questions have come up when working on this lab?

Answer all lab question after the conclusion
o -10 for questions that are not answers
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HHMenezes, Unit 4
Chemistry Laboratory Cover Sheet (Include on front of your Beanium lab!!!)
Name: ___________________________________ Period: ______
Lab Partners:___________________________________________
Lab Number:_________
Title:___________________________________
Introduction
Purpose/ Question
2 0
______
Hypothesis
5 0
______
Background information
8 5
0 ______
Results
Data
 Qualitative
5 2 0
______
 Quantitative in chart
10 5 0
______
 Units
5 0
______
Data Analysis
 Qualitative Observation
5 2 0
______
 Equations
2 0
______
 Calculations
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6 0
______
 Data Analysis Equations
5 0
______
Conclusion
 Restate Purpose/Hypothesis
3 0
______
 Accept or reject
1 0
______
o Support
4 2 0
______
Discussion
 Scientific Principle
1 0
______
o Why
4 2 0
______
 Does the procedure work?
5
1 0
______
Error
 Error
2 0
______
 How did it affect data
2 0
______
 How did it affect results
6 3 0
______
Questions
 New Question
2 0
______
 Questions Answered
Total of 10
______
Total Grade_______
All Labs must be typed!
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
SWS 4.02 – Isotopes/Ions
NAME: ______________________ (page 1)
Isotopes/Ions Worksheet
1. What is an isotope?
_____________________________________________________________________
2. What does the number next to isotopes signify? ______________________________________________
3. How can you tell isotopes apart? __________________________________________________________
4. Which isotope appears on the periodic table? ________________________________________________
Instructions for tables 4-9: For each isotope write the number of protons, neutrons, and electrons.
5
# of protons
Vanadium-49
Vanadium-50
6
# of protons
# of neutrons
# of neutrons
# of electrons
# of electrons
7
# of protons
Nitrogen-13
Nitrogen-15
8
# of protons
# of neutrons
# of neutrons
# of electrons
# of electrons
9
# of protons
Magnesium-23
Magnesium-24
10
# of protons
# of neutrons
# of neutrons
# of electrons
# of electrons
Carbon-12
Carbon-14
Chlorine-36
Chlorine-37
Selenium-72
Selenium-82
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HHMenezes, Unit 4
(Page 2)
Instructions for tables 11-20. Fill in the isotope names and any missing information, including isotope
numbers from the chart. Use your periodic table and the information provided.
12
# of protons
11
# of protons
27
15
# of neutrons
# of neutrons
15
18
# of electrons
13
# of protons
57
61
# of electrons
46
Iron-
# of neutrons
79
82
# of electrons
55
Iodine-
Iodine-
# of neutrons
28
30
# of electrons
Zirconium-
Zirconium-96
72
76
# of electrons
18
-
-
205
# of protons
# of neutrons
53
# of electrons
# of electrons
16
# of protons
Iron-
# of neutrons
17
# of protons
33
14
# of protons
# of neutrons
15
# of protons
29
81
# of neutrons
127
# of electrons
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HHMenezes, Unit 4
(Page 3)
19
# of protons
Uranium-235
-
20
# of protons
# of neutrons
Americium-241
# of neutrons
146
148
# of electrons
# of electrons
92
Instructions for table 21: For each ion write the number of protons, neutrons, and electrons.
Ion
Atomic
Number
AMU
# of
protons
# of
neutrons
Ca2+
Iodide
Phosphide
Chloride
N3-
Write the above chemicals in symbol form:
and Name-Z.
# of
electrons
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4.03 – Atomic Composition
Element
Symbol
Atomic
Number
Atomic
Mass
Unit
NAME: ______________________
# of
Protons
# of
# of
Charge
Neutrons Electrons
Te
33
16
81
Pt
U
-2
+3
42
16
123
54
16
+1
92
+2
23
28
20
Y
35
15
36
31
-3
Carbon
8
Ti
Helium
Cr
+6
19
18
65
84
75
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
NAME: ______________________
Discussion Sheet 4c – Finding Average Atomic Mass
You may be wondering why some of the atomic mass numbers in the periodic table are expressed in decimal notation, and not
whole numbers. After all, an atom’s mass is the sum of its protons and neutrons, and it is impossible for an atom to have a
fraction of a proton or a neutron. The reason why the periodic table contains decimals is because the atomic mass number in
the periodic table represents the average mass of all of the known isotopes of a given element. Isotopes are atoms that have
the same number of protons but different numbers of neutrons. Some atoms of an element can therefore be heavier than
other atoms, due to an extra neutron in the nucleus.
Some of the carbon found in nature has a mass of 12 (6 protons and 6 neutrons in the nucleus). This isotope of carbon is called
Carbon-12. Some of the carbon found in nature is heavier, due to the presence of an extra neutron. This type of carbon is
called Carbon-13, and has 6 protons and 7 neutrons. The periodic table entry for carbon has an atomic mass of 12.011. Since
this number is so close to 12, we can assume that most of the carbon found in nature is Carbon-12. How does a scientist
calculate an average atomic mass? Well, let’s consider the following problem.
A family contains the following four people. Find the average weight of the family members.
100 pounds
100 pounds
100 pounds
104 pounds
Traditionally, a math student will do this problem by adding up all four of the weights and then dividing by 4, the number of
people in the family. This will get the correct answer, which is 101 pounds:
100 + 100 + 100 + 104
------------------------------4
=
101
Here’s another way of looking at this question:
3 out of 4 people in the family are 100 pounds. 3 out of 4 is 75% of the family.
1 out of 4 people in the family are 104 pounds. 1 out of 4 is 25% of the family.
75% × 100 pounds
+ 25% × 104 pounds
-----------------------------100% × Average weight
=
=
7500
+ 2600
----------
=
10100
=
100% × 101 pounds
By multiplying each percentage by the appropriate weight, and then adding them all up, we can determine what the average of
100% of the family members will be.
The first method is not useful for calculating average atomic mass because we don’t have the necessary variables. You will find
the second method to be far more convenient and effective when you are trying to find the average atomic mass. Remember to
make sure that all percentages add up to 100%.
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4.04 – Average Atomic Mass
NAME: ______________________
Solve the following problems. Use the solution to the example problem as a guide.
1. Use the following information to determine the average atomic mass of chlorine. Two
isotopes are known: chlorine-35 and chlorine-37. The relative abundance of chlorine-35 is
75.4%.
2. A research team has just discovered a new element called Likhitium. Now, they need to
determine the average atomic mass in order to complete an entry for the periodic table.
Given the following relative abundances, calculate the average atomic mass of Likhitium.
Likhitium-138:
44.7%
Likhitium-139:
52.3%
Likhitium-140:
00.5%
Likhitium-141:
02.5%
3. Another new element, Thorsonium, has two isotopes. 67.52% of the Thorsonium isotopes
have a mass of 256 amu. The rest of the sample is Thorsonium-257. Find the average
atomic mass of Thorsonium.
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4.05 – More Average Atomic Mass
NAME: ______________________
Solve the following problems.
1. There are four isotopes of lead. Data on their atomic structure can be found in the table.
Find the average atomic mass of lead in the space below.
Isotope
Protons
Neutrons
Percent Abundance
A
82
122
1.37%
B
82
124
26.26%
C
82
125
20.82%
D
82
126
51.55%
2. A new element, Albanesium, has been discovered. 43.2% of all naturally occurring
Albanesium has a mass of 292 amu. 46.8% of all Albanesium has a mass of 293 amu. The
rest of the Albanesium has a mass of 295 amu. Find the average atomic mass of Albanesium.
3. There are two naturally occurring isotopes of Beinium, of respective masses 670 and 682.
What percentage of a natural sample is of mass 670 if the periodic table entry reads
671.82? (Remember – all percentages have to add up to 100%.)
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
NAME: ______________________
Laboratory Activity 4B – Average Atomic Mass of Beanium
The Atomic Mass of Beanium
You should create a complete lab report for this Laboratory Activity.
Intro: In this lab you will calculate the average mass of the element “Beanium” by taking a sample of this
element
and taking a weighted average of its three isotopes – black, red, and pinto. Read the directions before
beginning the laboratory activity. Modify the directions before proceeding if you see fit to do so.
Materials: Sample of Beanium, Balance, and a Dixie Cup
Procedure:
1. Obtain 1 full Dixie cup of Beanium from the source container.
2. Separate your sample into the 4 types of beans and label as RED = A, WHITE = B, and PINTO = C., Blackeyed=D
3. Carefully follow the instructions given in the second column of the Data Table below.
4. When your Data Table is complete return your sample of Beanium to the source container.
Data Table:
Beanium Isotopes
1. Total Mass of
each isotope (g)
2. Number of
atoms
3. Average Mass
per particle (g)
4. Relative
Abundance
5. Percent
Abundance (%)
Instructions
Measure the mass of
all the particles in
each isotope to the
nearest 0.001g
Count the number of
particles or “atoms”
for each isotope.
Divide the total mass
by the number of
atoms for each
isotope.
Divide the number of
atoms in each isotope
by the total number
of Beanium atoms
altogether.
Multiply the relative
abundance of each
isotope by 100.
A
(RED)
B (WHITE)
C (PINTO)
D
(Blackeyed)
Totals
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HHMenezes, Unit 4
MUST DO LAB REPORT FOR BEANIUM LAB
Introduction: The following should be included in your introduction:
1. Define isotopes
2. Explain the difference between relative abundance and percent abundance.
3. Give a made up story for Beanium (funny=more points!)
Analysis: The following should be included in your analysis section
4. Calculate the weighted average mass of Beanium atoms using the information in the Data
Table in parts 3 and 5. Hint: This is the average atomic mass of Beanium.
5. Compare your teams average atomic mass of Beanium to 2 other teams calculated number.
a. Your team = _______________________
b. 1st Other team = ____________________
c. 2nd Other team =____________________
6. Were your results exactly the same? ____________ Why might they be different?
Finally, explain to me how Beanium and the procedures you have used to analyze it are analogous
to isotopes of atoms found in nature and the atomic masses listed on the periodic table
21
HHMenezes, Unit 4
– Introductory Atomic Theory
Worksheet 4R – Review (Page 1)
NAME: ______________________
1. True or False. Make the False statements true.
a. _____ The number of neutrons in an atom is referring to its atomic number.
b. _____ The periodic table is arranged by increasing atomic number.
c. _____ Atomic number is equal to the number of electrons in an atom.
d. _____ The number of protons in an atom identifies it as an atom of a particular
element.
e. _____ Most atoms have either a positive or a negative charge.
2. Determine the symbol for the following atoms, ions, or isotopes.
a. An atom has atomic number 19 and mass number of 39.
b. An isotope has 14 electrons and a mass number of 28.
c. An ion has 21 neutrons and mass number of 40 with a charge of 2+.
3. What is the percent abundance for chlorine-35. The mass of 35Cl is 34.969 and the mass of
37
Cl is 36.966. The atomic mass unit is 35.453 amu.
4. Calculate the atomic mass unit for europium based off the following data.
Mass
Percent
Abundance
62.930
69.17
64.928
30.83
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HHMenezes, Unit 4
Unit 04 – Introductory Atomic Theory
Worksheet 4R – Review (Page 2)
Element
Symbol
Atomic
Number
Atomic
Mass
Unit
NAME: ______________________
# of
Protons
# of
Neutrons
# of
Electrons
Charge
Tc
37
1190
53
8
Sulfur
Pb
4+
54
18
34
2-
209
56
Write the above chemicals in symbol form:
and Name-Z.
54
23