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Name: ____________________________________________________ Period: _______ Teacher: ____________
Unit 4 –The Atom (Level)
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13
14-15
16
19
20
21-22
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Vocabulary
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
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Protons/Neutrons/Electrons
Isotopes
Ion
Concepts
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Scientists contribution to the atom
Atomic structure
Isotopes and Ions
Mass Number vs Average atomic mass
Calculating % abundance
Calculating % composition
Objectives:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Name and identify the subatomic particles of an atom.
Describe the charge, mass, and location of the subatomic particles.
Trace the development of modern atomic theory
Compare and contrast the atomic models of Democritus, Dalton, Thomson, Rutherford, Chadwick, Bohr, Schrodinger
Identify an element based on the number of protons.
Calculate the number of electrons, protons, and neutrons in an atom given its mass number and atomic number.
Draw a Bohr model for a particular isotope (honors may include ions)
Define an isotope and explain why atomic masses are not whole numbers.
Calculate the atomic mass of an element given the abundance of the isotopes.
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Warm-ups
Mon, Sept. 12
Tues, Sept. 13
Thurs, Sept. 15
Fri, Sept. 16
Mon, Sept. 19
Tues, Sept. 20
Thurs, Sept. 22
Fri, Sept. 23
3
Atomic History Notes
Scientist
Democritus
John Dalton
JJ Thompson
Ernest
Rutherford
James
Chadwick
Niels Bohr
Contribution
Sketch of Atomic Model
4
Atomic Sketches
Directions: You will be assigned an element from your teacher. In each of the circles, you must draw a
representation of your atom as you think that scientist would have seen it. In the boxes next to the arrows,
you must write how the atom is changing from one scientist to the other.
Democritus
Niels Bohr
John Dalton
JJ Thompson
James Chadwick
Ernest Rutherford
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Atoms in a Bag
Directions: For each bag, count the number of protons (____________________), the number of neutrons
(_____________________) and the number of electrons (____________________). Then answer the questions that
follow.
Bag A
Bag B
Bag C
# of protons: _____
# of protons: _____
# of protons: _____
# of neutrons: _____
# of neutrons: _____
# of neutrons: _____
# of electrons: _____
# of electrons: _____
# of electrons: _____
Bag D
Bag E
Bag F
# of protons: _____
# of protons: _____
# of protons: _____
# of neutrons: _____
# of neutrons: _____
# of neutrons: _____
# of electrons: _____
# of electrons: _____
# of electrons: _____
Bag G
Bag H
Bag I
# of protons: _____
# of protons: _____
# of protons: _____
# of neutrons: _____
# of neutrons: _____
# of neutrons: _____
# of electrons: _____
# of electrons: _____
# of electrons: _____
Bag J
# of protons: _____
# of neutrons: _____
# of electrons: _____
Analysis Questions:
1.
What do Bags A, B, E, F, H and J have in common?
2. Which bags do you think are different elements? Explain your answer.
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3. Compare the size of the proton and neutron. What conclusion can you reach?
4. Compare the size of the proton and the electron. What conclusion can you reach?
5. Look at the locations of the proton, neutron and electron. Where is the majority of the atom’s mass located?
6. Compare and contrast bags B and F. Note all similarities and differences.
7. Which other pair of bags is like bags B and F? Explain your answer.
8. Compare and contrast bags C and I. Note all similarities and differences.
9. Which other pair of bags is like bags C and I? Explain your answer.
10. Predict what the number of protons in the atom means.
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Atomic Structure Notes
What is an atom?
Subatomic Particle
Proton
Neutrons
Electrons
Location
Charge
Mass
Which 2 subatomic particles are equal in number to each other? _______________________________________
What is the atomic number and where can it be found?
What is the atomic number in the atom to the right? _____ Why? _____________________________
What is the mass number?
What is the mass number in the atom to the right? _____ Why? ______________________________
AZ Notation – How to express an atom’s atomic number and mass number
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14
7N:
How many protons? ____ Electrons? ____ Neutrons?__
16 S: Protons? _____ Electrons? ______ Neutrons? ____
35
17Cl: Protons? ______ Electrons? _________ Neutrons? _____
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What is an isotope?
How is the isotope of an atom expressed?
How to Draw a Bohr Model
Which subatomic particles would be drawn in the center of the atom?
How do you determine the number of subatomic particles to put in your Bohr Model?
Energy Level
Max # of Electrons
1
2
3
4
Examples:
Nitrogen – 14
Chlorine - 35
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6
7
8
Atomic Structure
1.
2.
3 subatomic particles:
a. _____________________________________
Their charge:
______________________________________
b.
_____________________________________
______________________________________
c.
_____________________________________
______________________________________
The number of protons in an atom of an element determines the atom’s _____________________________ and equals the
number of _________________________ in a neutral atom.
3.
The atomic number tells you the number of ___________________________ in one atom of an element. It also is referred to as
the identity of the atom, because no two elements will have the same ________________________.
4.
The _____________________________ of an element is the average mass of an element’s naturally occurring isotopes. This
takes into account the _____________________________ of each isotope.
5.
The ______________________ of an element is the total number of protons and neutrons in the _______________ of an atom.
6.
The mass number is used to calculate the number of _______________ and ______________ in one atom of an element. In
order to calculate the number of neutrons you must subtract the ______________________from the _____________________
___________________________.
7.
8.
Name the following elements using isotopic notation:
a.
26 electrons, 29 neutrons, 26 protons ___________________________________
b.
53 protons, 74 neutrons ______________________________________________
c.
2 electrons, neutral atom _________________________________________________________
True/Flase: If you know only the following information you can always determine what the element is.
a.
Number of protons: ______________________________________
b.
Number of neutrons: ______________________________________
c.
Number of electrons in a neutral atom: _______________________
BUILD AN ATOM:
Draw the Bohr model for the atoms below.
The dotted line indicates the nucleus.
Carbon-13
Oxygen-15
Sodium-23
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Composition of Neutral Atoms and Isotopes
Element
Element
Symbol
Name
p+
Li
lithium
3
Mass
Atomic
2 ways of showing
no
e-
No.
No.
the isotope
4
3
7
3
30
N
Li-7
64
8
Ra-226
carbon
6
34
16
I-131
Co-60
45
38
sodium
23
18
Cu
18
36
16
33
80
92
Hg-201
235
Ag-108
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Isotopes & Ions Worksheet
I. Determine the charges on the following ions:
1. An atom having lost two electrons ________
5. An atom having lost five electrons ________
2. An atom having lost six electrons ________
6. An atom having gained two electrons ________
3. An atom having gained one electron ________
7. An atom having lost one electron ________
4. An atom having gained three electrons ________
8. An atom having gained four electrons ________
Questions:
1. If Li loses an electron to another atom, why does it have a have a +1 charge? ________________________________________
2. If N gains 3 electrons from other atoms, why does it have a -3 charge? _____________________________________________
Fill in any missing information for the IONS below.
Ion
Symbol
Iodine
I-1
B+3
Oxygen
Atomic
Number
Mass Number
Protons
127
53
35
79
5
11
O-2
16
54
8
7
Al+3
27
Fe+2
56
Cu+1
Electrons
36
Nitrogen
Aluminum
Neutrons
7
10
10
26
24
29
34
63
29
27
Fill in any missing information for the following atoms, isotopes, and ions.
Symbol
Indicate Charge
-2
207
82
Pb
Atomic
number
Protons
Neutrons
8
9
77
54
11
12
10
35
45
36
+2
12
238
92
U
Electrons
10
Mass
number
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Name __________________________________ Magic Square: Atomic Structure and Theory
Directions: Put the number of the definition from the list below into the square with the appropriate term.
Check your answers by adding the numbers to see if all the sums of all rows, both across and down add up to
the same number, the Magic #.
Law
Dalton
Thomson
Chadwick
Total
_____
_____
_____
______
_____
Rutherford
Proton
Atom
Plum pudding
_____
_____
_____
_____
Welch
Neutron
Nucleus
Gold Foil
_____
_____
_____
_____
Electron
Theory
Empty Space
Matter
_____
______
_____
_____
Total _____
_____
_____
_____
_____
_____
______
Magic Number ______
1. Represented by a symbol; all are found on the Periodic Table
2. A statement of what always happens in the natural world.
3. Used by Rutherford in his famous experiment.
4. Most of the volume of the atom consists of this.
5. The positive particle in the nucleus of an atom
6. The tiny positive core of an atom; contains protons and neutrons
7. Developed the first atomic theory based on science.
8. Discovered the nucleus, and realized that the atom is mostly empty space.
9. Anything with mass and volume.
10. A well-tested explanation of what happens in the natural world.
11. The smallest particle of an element that has the properties of that element
12. Discovered the neutron
13. The best chemistry teacher ever!!
14. Mass of protons and neutrons
15. The model of the atom proposed by J.J. Thomson
16. The negative particle that circles the nucleus
17. The neutral particle in the nucleus of an atom
18. Discovered the electron
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Average atomic mass & Percent abundance
Must show all work or no credit will be given!
1. Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208. The average atomic mass of a lead atom is
207.2 amu. Which isotope of lead is likely to be the most abundant?
2. Magnesium has three isotopes, Mg-24 (78.99%), Mg-25 (10.00%) and, Mg-26 (11.01%). Calculate the average
atomic mass of magnesium.
3. Tellurium has eight isotopes: Te-120 (0.09%), Te-122 (2.46%), Te-123 (0.87%), Te-124 (4.61%), Te-125 (6.99%), Te126 (18.71%), Te-128 (31.79%), and Te-130 (34.48%). What is its average atomic mass?
4. A certain element exists as three different isotopes, 24.1% of all the isotopes have a mass of 75.23 amu, 48.7% have
a mass of 74.61 amu, and 22.2% have a mass of 75.20 amu. What is the average atomic mass of this element and
determine which element this is.
5. Bromine has two naturally occurring isotopes. Bromine-79 and bromine-81. Find the % of each naturally occurring
isotope in nature.
6. Silver has two naturally occurring isotopes. Ag – 109 and Ag 107. Find the % of each naturally occurring isotope in
nature.
7. Antimony has two naturally occurring isotopes. The mass of antimony-121 is 120.904 amu and the mass of
antimony-123 is 122.904 amu. Using the average mass from the periodic table, find the abundance of each isotope.
8. What is the percent composition of 85 g Iron in a 947 g mixture?
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Atomic History and Structure Review
1.
2.
Explain the contributions of the following scientists to the study of the atom:
a.
Neils Bohr: ____________________________________________________________________________
b.
John Dalton: ___________________________________________________________________________
c.
Democritus: ___________________________________________________________________________
d.
Ernest Rutherford: ______________________________________________________________________
e.
JJ Thompson: __________________________________________________________________________
Identify each of the following as a true or false statement. If false, correct the underlined portion.
a.
Protons and electrons are located in the nucleus of the atom.
b.
Protons and neutrons have relatively the same charge.
c.
In a neutral atom, the number of protons and electrons are the same.
d.
The electron is equal to the atomic number and identifies the atom as being that of a specific element.
e.
The number of protons and neutrons is equal to the atomic number of the atom.
f.
The majority of the atom’s mass is located inside the nucleus.
3.
What is the difference between an isotope and an ion?
4.
A Nitrogen ion gains 3 electrons. What is the correct symbol and charge? ___________________
5.
A Manganese ion loses 4 electrons. What is the correct symbol and charge? _________________
6.
Complete the following chart.
Symbol
Element Name
p+
no
e-
Mass
#
Atomic
#
2 ways of showing the isotope
Zirconium-94
18
20
Fluorine
19
64
112
78
198
87
223Fr
7.
Draw a Bohr model for the following neutral atoms:
Oxygen
Sodium
14
8.
What is the difference between atomic mass and mass number?
9.
Argon has 3 naturally occurring isotopes: Ar-36, Ar-38 and Ar-40. Which is the most common isotope, why?
10. Lithium has 2 natural occurring isotopes, Li – 6 and Li – 7. Determine the percent abundance of each of lithium’s isotopes.
11. Gallium occurs in nature as a mixture of two isotopes. They are Ga-69 with a 60.108% abundance and a mass of 69.926 amu
and Ga-71 with a 39.892% and an atomic mass of 70.925 amu. Calculate the atomic mass of gallium. Use appropriate number
of sig figs.
12. A 84.30g Sample of aspirin is made up of 5.02 g hydrogen, 60.12 g Carbon and 19.16 g of oxygen. What is the percent
composition of Carbon in the sample?