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*STUDENT*
*STUDENT*
Regents Chemistry
PRACTICE PACKET
Unit 2: Atomic Theory
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Copyright © 2015 Tim Dolgos
Name ____________________________
History of Atomic Theory
Period _______
Fill in the missing information in the chart below:
Name of Researcher
Equipment/
Experiment
Sketch of Model
Major Idea/Discovery
N/A
All atoms of a given
element are identical in
mass and properties
N/A
Electrons travel around
the nucleus in welldefined paths called
orbits (like planets in a
solar system)
Thomson
Rutherford
Electrons have distinct
amounts of energy and
move in areas called
orbitals
Developed after the
famous discovery that
energy can behave as both
waves & particles
N/A
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Copyright © 2015 Tim Dolgos
Atomic Structure Worksheet
**Assume all are neutral atoms!
Fill in the blanks in the following worksheet. Please keep in mind that the isotope
represented by each space may NOT be the most common isotope or the one closest in
atomic mass to the value on the periodic table.
Atomic
symbol
C
Atomic
number
Protons
Neutrons
Electrons
Mass
number
8
12
24
31
40
40
30
89
35
42
98
W
183
105
95
71
243
Cr
27
83
209
90
142
Md
259
Se
80
40
51
Notice there are two different atoms of zirconium (Zr) listed. These different
versions are called ISOTOPES. What one subatomic particle is different
from one isotope to the other? __________________________________
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Copyright © 2015 Tim Dolgos
Atomic Theory- Neutral Atoms and their subatomic parts
**IMPORTANT**If the mass number is not given to you, round the
atomic mass that you find on the Periodic Table for that element.
How many protons, neutrons, and electrons are present
in the following neutral atoms?
vanadium
potassium
P=
N=
e=
nitrogen
platinum
argon
helium
What is the name of the element that has neutral atoms that contain:
5 protons?
16 electrons?
_____________________
_____________________
17 protons?
32 electrons?
_____________________
_____________________
25 protons?
1 electron?
_____________________
_____________________
82 protons?
8 electrons?
_____________________
_____________________
92 protons?
2 electrons?
_____________________
_____________________
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Copyright © 2015 Tim Dolgos
Complete the following chart: (assume the overall charge on all atoms = 0….except the last one!)
Element
Symbol
Atomic
Number
# of
Protons
Hydrogen
# of
Neutrons
Mass
Number
(amu)
1
He
4
Na
12
Potassium
39
20
20
26
30
Rb
86
Carbon
6
Xenon
131
16
At
15
126
14
Copper
7
64
Ne
10
23
Lithium
Ion
# of
Electrons
Li+
27
3
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Copyright © 2015 Tim Dolgos
P, n, e of ions
**IMPORTANT**If the mass number is not given to you, round the
atomic mass that you find on the Periodic Table for that element.
Write the full chemical symbol for the ion with:
1) 12 protons and 10 electrons:
P=
N=
e=
2) 74 protons and 68 electrons:
3) 95 protons and 89 electrons:
4) 33 protons and 36 electrons:
Determine the number of p, n, e for the following ions:
Cu2+
Li+
O2-
Al3+
I7+
p=
n=
e=
Cl-
# protons
Lithium1+
# electrons
# neutrons
3
Phosphorus3-
18
31
23
Krypton0
Uranium5-
Mass #
4
Vanadium0
Barium4+
Atomic #
48
56
51
36
137
97
146
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Copyright © 2015 Tim Dolgos
For the following atoms/ions determine the number of protons, neutrons,
electrons, mass number, and nuclear charge.
ATOM
or ION?
PROTONS
NEUTRONS
ELECTRONS
MASS
NUMBER
NUCLEAR
CHARGE
15
N
Cu+2
8 +3
B
17
O
F-1
206
Pb
208
Pb
Ag+1
Zn+2
Mg
S-2
Question: Which of the above atoms are isotopes of one another? Explain
how you know this. ___________________________________________
_________________________________________________________
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Copyright © 2015 Tim Dolgos
ATOM
or ION?
PROTONS
NEUTRONS ELECTRONS
MASS
NUMBER
NUCLEAR
CHARGE
Al+3
37
Cl
23
Na+1
He
15
O-2
14
C
C
Au+3
U
222
Rn
Cu+1
Cu+2
Question: Which of the above atoms are isotopes of one another? Explain
how you know this. ___________________________________________
_________________________________________________________
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Copyright © 2015 Tim Dolgos
Calculate the atomic mass of each of the following isotopes. SHOW ALL WORK.
Element
Mass
Percent Abundance
1)
copper-63
copper-65
62.9396 amu
64.9278 amu
69.17%
30.83%
2)
uranium-235
uranium-238
235.0439 amu
238.0510 amu
0.72%
99.28%
3)
hydrogen-1
hydrogen-2
1.0078 amu
2.0140 amu
99.985%
0.015%
4)
element Q-8
element Q-9
element Q-10
8.0 amu
9.0 amu
10.0 amu
10.0%
20.0%
70.0%
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Copyright © 2015 Tim Dolgos
Weighted Averages HW (SHOW ALL WORK!)
Name _____________________
*You can round the masses given to you or use them as given – just be consistent!
1) Element X exists in three isotopic forms. The isotopic mixture consists of 10.0% 10X,
20.0% 11X, and 70.0% 12X. What is the average atomic mass of this element?
2) Element Y exists in three isotopic forms. The Isotopic mixture consists of 15.0% 21X,
65.0% 22X, and 20.0% 23X. That is the average atomic mass of this element?
3) A mystery element occurs in nature as two isotopes. Isotope A has a mass of 10.0130
amu and its abundance is 19.9%; Isotope B has a mass of 11.0093 amu and its
abundance is 80.1%. From this data, calculate the atomic mass of the element and
show all work. Lastly, identify the element.
4) A mystery element occurs in nature as two isotopes. Isotope A has a mass of
62.939598 amu and its abundance is 69.17%; Isotope B has a mass of 64.927793 amu
and its abundance is 30.83%. From this data, calculate the atomic mass of the
element and show all work. Lastly, identify the element.
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Copyright © 2015 Tim Dolgos
5) A mystery element occurs in nature as three isotopes. Isotope A has a mass of
15.994915 amu and its abundance is 99.762%; Isotope B has a mass of 16.999132 amu
and its abundance is 0.0380%; Isotope C has a mass of 17.999160 amu and its
abundance is 0.2000%. From this data, calculate the atomic mass of the element and
show all work. Lastly, identify the element.
Isotopes and Average Atomic Mass
Example: A sample of cesium is 75% 133Cs, 20%
the average atomic mass?
132
Cs, and 5%
134
Cs. What is
Determine the average atomic mass of the following mixtures of isotopes.
1. 80%
127
I, 17% 126I, 3% 128I
2. 50%
197
Au, 50% 198Au
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3. 15%
55
56
Fe, 85%
Fe
4. 99% 1H, 0.8% 2H, 0.2% 3H
5. 95%
14
N, 3%
15
N, 2%
16
N
6. 98% 12C, 2% 14C
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Copyright © 2015 Tim Dolgos
Regents Chemistry
Name _________________________
Principal Energy Level Worksheet
Element
Carbon
e-configuration
1s __
2s __ 2p __ __ __
Helium
1s __
Neon
1s __
2s __ 2p __ __ __
Oxygen
1s __
2s __ 2p __ __ __
Sulfur
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
Aluminum
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
Sodium
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
Lithium
1s __
2s __ 2p __ __ __
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Calcium
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __
Fluorine
1s __
2s __ 2p __ __ __
Chlorine
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
Hydrogen
1s __
Magnesium
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
Tin
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __
5s __ 5p __ __ __ 5d __ __ __ __ __ 5f __ __ __ __ __ __ __
Potassium
1s __
2s __ 2p __ __ __
3s __ 3p __ __ __ 3d __ __ __ __ __
4s __ 4p __ __ __ 4d __ __ __ __ __ 4f __ __ __ __ __ __ __
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Copyright © 2015 Tim Dolgos
Construct Bohr diagrams for the following:
Na
electron configuration ___________ F
O
electron configuration ___________ Li
+
electron configuration ___________
Cl-
electron configuration ___________ Ne
electron configuration ___________
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electron configuration ___________
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Copyright © 2015 Tim Dolgos
Draw Lewis Dot Diagrams for the following:
Charge ____
# Valence e- ____
N
Charge ____
# Valence e- ____
C
# unpaired valence e- ____
# of bonds _____
# unpaired valence e- ____
# of bonds _____
Charge ____
# Valence e- ____
Charge ____
# Valence e- ____
Li+
He
# unpaired valence e- ____
# of bonds _____
# unpaired valence e- ____
# of bonds _____
Charge ____
# Valence e- ____
Charge ____
# Valence e- ____
O
B
# unpaired valence e- ____
# of bonds _____
# unpaired valence e- ____
# of bonds _____
Charge ____
# Valence e- ____
Charge ____
# Valence e- ____
S
Kr
# unpaired valence e- ____
# of bonds _____
# unpaired valence e- ____
# of bonds _____
Charge ____
# Valence e- ____
Charge ____
# Valence e- ____
Se2-
# unpaired valence e- ____
# of bonds _____
Ca+2
# unpaired valence e- ____
# of bonds _____
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Copyright © 2015 Tim Dolgos
Bohr and Lewis Dot Diagrams
Element
Carbon
p=
n=
e=
Oxygen
p=
n=
e=
Sodium
Electron
Configuration
# Valence e# Kernel e-
Lewis Dot
Diagram
Valence e- =
Kernel e- =
Valence e- =
Kernel e- =
Valence e- =
p=
n=
e=
Kernel e- =
Neon
Valence e- =
p=
n=
e=
Bohr Diagram
Kernel e- =
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Copyright © 2015 Tim Dolgos
Bohr and Lewis Dot Diagrams (continued)
Element
Fluorine
p=
n=
e=
Argon
p=
n=
e=
Nitrogen
Electron
Configuration
# Valence e# Kernel e-
Lewis Dot
Diagram
Valence e- =
Kernel e- =
Valence e- =
Kernel e- =
Valence e- =
p=
n=
e=
Kernel e- =
Lead
Valence e- =
p=
n=
e=
Bohr Diagram
Kernel e- =
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Copyright © 2015 Tim Dolgos
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Copyright © 2015 Tim Dolgos
Regents Chemistry
Electron Configuration Worksheet
Name _________________________
Period ____
For the questions 1-10, assume all atoms are neutral. Use the electron configurations to
determine the identity of the element and whether it is in the ground or excited state.
Electron Configuration
1.
2-8-1
2.
2-8-16-3
3.
2-8-2
4.
2-7-8
5.
1-3
6.
2-8-6
7.
-18-32-18-4
8.
-18-32-17-3
9.
2-7
10.
1-8
Identity
Ground/Excited
Give an electron configuration for the following:
11. Sulfur in its ground state.
12. Helium in an excited state.
13. Give the ground state electron configuration for calcium. _____________________
14. Give the correct electron configuration for the Ca+2 ion. ______________________
15. How many valence electrons are there in atom of bromine? ________
16. How many valence electrons are there in a Cl- ion? ________
17. How many kernel electrons are there in a phosphorus atom? ________
18. How many valence electrons are there in a neon atom? ________
19. How many principal energy levels are there in a iron atom? ________
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Copyright © 2015 Tim Dolgos
20. When atoms of an element are emitting a certain wavelength (or color) of light, it
means that
a) the atoms have gained energy and electrons have jumped to an excited state.
b) the atoms have gained energy and electrons have fallen back to the ground
state.
c) the atoms have lost energy and electrons have fallen back to the ground state.
d) the atoms have lost energy and electrons have jumped to an excited state.
Use the emissions spectra results below to answer questions 14 and 15:
Gas A
Gas B
Gas C
Gas D
Unknown Gas
21. According to these experimental spectra results, the unknown gas is a mixture of
which gases? ___________
22. The lines on the visible light spectrum for the gases above represent
a) electrons jumping to the same excited state or energy level.
b) electrons falling back down to their ground state from the same energy level.
c) electrons jumping to multiple excited states or energy levels.
d) electrons falling back down to their ground state from multiple energy levels.
23. How do the energy and the most probable location of an electron in the third
shell of an atom compare to the energy and the most probable location of an
electron in the first shell of the same atom?
a) In the third shell, an electron has more energy and is closer to the
nucleus.
b) In the third shell, an electron has more energy and is farther from the
nucleus.
c) In the third shell, an electron has less energy and is closer to the
nucleus.
d) In the third shell, an electron has less energy and is farther from the
nucleus.
24. An atom of oxygen is in an excited state. When an electron in this atom moves
from the third shell to the second shell, energy is
Copyright © 2015 Tim Dolgos
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a)
b)
c)
d)
emitted by the nucleus
absorbed by the nucleus
emitted by the electron
absorbed by the electron
25. Which electron configuration could represent a strontium atom in an excited
state?
a) 2–8–18–7–1
b) 2–8–18–8–1
c) 2–8–18–7–3
d) 2–8–18–8–2
26. Imagine an emission spectrum produced by a container of hydrogen gas.
Changing the amount of hydrogen in the container will change the colors of the
lines in the spectrum.
a) True
b) False
27. In the previous question, changing the gas in the container from hydrogen to
helium will change the colors of the lines occurring in the spectrum.
a) True
b) False
28. An absorption spectrum appears as a continuous spectrum interrupted by a
series of dark lines.
a) True
b) False
29. Emission spectra are characterized by narrow bright lines of different colors.
a) True
b) False
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Copyright © 2015 Tim Dolgos