L3 CHEMISTRY MIDTERM REVIEW
Friday Jan
18th,
Name
Answer KEY
Essay Day:
The components of Chemistry are extremely small, therefore chemists use models in order to represent and understand
information on the subatomic level. Many of the models we use can tell us similar information but it is up to us to
determine which models best represent the information we are trying to determine.
You will be responsible for analyzing and interpreting the following models:
 Periodic Table
 Half – Life Graphs
 Bohr’s Solar System Model
 Orbital Box Diagrams
Think to yourself, “What does this model represent?” and “What does this model tell me?”
Atomic Models
1. Place the following atomic models in the correct order of discovery.
Thomson’s Plum
Pudding Model
1.
2.
3.
4.
5.
Bohr’s Planetary
Model
Quantum Mechanical
or Electron Cloud
Model
Dalton’s Atomic
Model
Rutherford’s Nuclear
Model
Dalton
Thomson
Rutherford
Bohr
Quantum Mechanical
2. Describe how the models have changed over time and what improvements have been made due to new
discoveries.
A. Dalton to Thomson – electrons were found. The atom is no longer a solid sphere instead there are electrons
spread throughout the positive atom.
B. Thomson to Rutherford – the nucleus is discovered. Solid nucleus while the rest of the atom is empty space
filled with electrons
C. Rutherford to Bohr – Electrons are now placed in energy levels or rings surrounding the nucleus. These energy
levels are specific distances apart.
D. Bohr to Quantum Mechanical Model – the electrons are found in specific energy levels but they are free to
travel in specific regions of space. These include orbitals. There are no defined boundaries for orbitals and
energy levels.
Atoms, Isotopes, Ions
Definitions- Define or fill in the following:
3. atomic number-
# of protons
4. mass number-
# of protons and neutrons
5. isotope-
atoms that differ in the number of neutrons (mass number) but have the same atomic number
6. ion-
atoms that have gained or lost electrons, atoms with a charge
7. protons have a
positive
charge and are found
in the nucleus
.
8. neutrons have a
neutral
charge and are found in the nucleus
.
9. electrons have a
negative
charge and are found
10. The
The
protons
and
neutrons
electrons
.
are about the same size and make up the mass of the atom.
are MUCH smaller and do not really affect the mass of the atom.
11. Two isotopes are the same in this way:
different in this way:
They contain the same number of protons and electrons
. They are
different number of neutrons therefore different mass number .
12. An ion is different from an atom because it has gained or lost
charge
the electron cloud
electrons
. It therefore has a
whereas an atom is neutral.
13. Complete the following table:
Name
Symbol Atomic # Mass # # p+ # n # e-
Oxide ion
16 −2
8𝑂
8
16
8
8
10
Barium atom
138
56𝐵𝑎
56
138
56
82
56
Hydrogen-2 atom
2
1𝐻
1
2
1
1
1
Chlorine-36 atom
36
17𝐶𝑙
17
36
17
19
17
Calcium ion
40
2+
20𝐶𝑎
20
40
20
20
18
sulfide ion
32 −2
16𝑆
16
32
16
16
18
14. Another name for a positive ion is cation
.
15. Another name for a negative ion is
anion .
16. Metals
cations .
lose
17. Nonmetals
electrons to form
gain
electrons to form anions
.
18. Explain the difference between the mass number of an element and the average atomic mass of the element.
mass number = protons + neutrons
average atomic mass = the sum of the percent abundance of a particular isotope times the mass number of that
particular isotope
Nuclear Chemistry
Fill in the correct type of radiation for each of the following statements:
Alpha
Beta
Gamma
19. The smaller of the particles
beta
20. The only one without mass
beta
or gamma
21. Can be stopped by paper
alpha
22. Needs a very thick piece of lead to stop it
gamma
23. Radiation of this type would be most damaging to you
gamma
Complete the following equations by writing the correct numbers and symbol for the missing particle in the
blank.
24.
212
84𝑃𝑜
25.
204
80𝐻𝑔
208
82𝑃𝑏
→ 42𝛼 +
→
0
−1𝛽
+
204
81𝑇𝑙
Radioactive Half- Life
26. Use the following graph to answer the following questions …
27. How long is a half-life for carbon-14?
5730 yrs
28. If only 25% of the carbon-14 remains, how old is the material containing the carbon-14?
10, 740 yrs old
29. If a sample originally had 120 atoms of carbon-14, how many atoms will remain after 16,110 years?
15 atoms of carbon-14
30. If a sample known to be about 10,740 years old has 400 carbon-14 atoms, how many atoms were in the
sample when the organism died?
1600 carbon-14 atoms
31. Use the following chart to answer the following questions
Radioactive Substance
Radon-222
Iodine-131
Radium-226
Carbon-14
Plutonium-239
Uranium-238
Approximate Half-life
4 days
8 days
1600 years
5,730 years
24,120 years
4,470,000,000 years
32. If we start with 8000 atoms of radium-226, how much would remain after 3,200 years? __2000________
33. If we start with 20 atoms of plutonium-239, how many would remain after 48,240 years? ___5_______
34. If we start with 60 atoms of uranium-238, how many remain after 4,470,000,000 years? ____30_____
35. If we start with 24 atoms of iodine-131, how many remain after 32 days? ___1.5________
Average Atomic Mass Problems
36. A sample of silver is 52.0% 107Ag and 48.0% 108Ag. Calculate its average atomic mass in amu.
𝑥 𝑎𝑚𝑢 = (. 52 × 107) + (. 48 × 108) = 107.48 𝑎𝑚𝑢
37. Isotopic data for lead is below. Use that to calculate the average atomic mass of lead in amu.
Isotope Percent Abundance
204
Pb
1.37%
206
Pb
26.26%
207
Pb
20.82%
208
Pb
51.55%
𝑥 𝑎𝑚𝑢 = (. 0137 × 204) + (. 2626 × 206) + (. 2082 × 207) + ( .5155 × 208) = 207.21 𝑎𝑚𝑢
Electromagnetic Radiation
38. What are the different characteristics of a wave?
39. When wavelength increases, frequency _____ decreases___________________. When wavelength decreases,
frequency ______ increases__________________.
40. Frequency and Energy are ______ directly____________________ related; which means that when frequency
increases, energy ____increases __.
41. If a wave has a very large wavelength, the energy of the wave is ____low/ small _______.
42. Describe what happens to the electrons in an atom to produce visible light. Use the Bohr Model to represent what
is occuring.
Photon is just the name for a quantum of light
Electron Transition – when an electron moves from one level to another
a. When an electron transitions to a higher energy level, a photon is absorbed.
b. When an electron transitions to a lower energy level, a photon is emitted.
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of
electromagnetic radiation emitted by the element's atoms or the compound's molecules when they are
returned to a lower energy state.
Below is an Electromagnetic Radiation Spectrum. Answer the following questions based on the information
provided.







Violet: 400-430 nm
Indigo: 430-450 nm
Blue: 450-500 nm
Green: 500-570 nm
Yellow: 570-590 nm
Orange: 590-610 nm
Red: 610-700 nm
43. What color of visible light has the longest wavelength? Red Smallest (Lowest) frequency? Red
44. Which has the highest frequency blue light or yellow light? Blue Lowest energy? yellow
45. Which has more energy X rays or FM radio waves? X rays (shorter wavelength)
Electron configurations
46. Fill in the following charts:
SubLevel
# of
Orbitals
# of
Electrons
s
1
2
p
3
6
d
5
10
f
7
14
Major Energy Level
The sublevels that exist
in this level
1
s
2
s&p
3
s,p &d
4
s, p, d & f
47. Give the electron configurations for the following atoms (both regular and box diagram). You may use the shortcut
for any atom in period 3 or larger:
Electron configuration
Orbital Box Diagram
a. Lithium – 1s2 2s1
1s
Lewis Dot Diagram:
b. Terbium (65)
Li ●
2s
# of valence electrons 1
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 5d1 4f8
[Xe]
6s
Lewis Dot Diagram:
c. Iodine (53)
5d
●
Tb ●
4f
valence electron configuration:
6s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5
[Kr]
5s
4d
Lewis Dot Diagram
●●
● ●I ●
●●
5px
py
# of valence electrons 7
Name one element with a similar valence configuration.
d. Rhodium (45)
pz
Any Halogen Group 7A
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d7
[Kr]
5s
Lewis Dot Diagram:
4d
●
Rh ●
# of valence electrons 2
Periodic Trends
The arrows show
the direction that
the trends
increase!!!
48. For the following pairs of elements, list the ones that have the greater electron affinity:
a. Oxygen and Fluorine - ____ F ________
b. Lithium and Cesium - ______ Li _______
(bigger love of electrons will be smaller in size)
across table increases
c. Silicon and Sulfur - _______Si________
down table decreases
d. Boron and Aluminum - _____ B _______
49. For the following pairs of elements, list the ones with the smaller atomic radius:
a.
Magnesium and Barium - ______Mg______stronger nuclear charge when going across the table
b.
Arsenic and Bromine - _________Br___
c.
Potassium and Zinc - _______Zn_______
d.
Neon and Xenon - _______Ne_________
less shells as you go down the table
50. For each of the following questions, write the symbol for the element described.
_____a.
In period 3, which element has the lowest ionization energy? Na
_____b.
In group 17 (7A), which element has the highest ionization energy? F
_____c.
What element has the lowest ionization energy of all the elements? Fr
_____d.
In period 2, which element has the smallest atomic radius? Ne
_____e.
Which halogen has the largest atomic radius? At
_____f.
What is the smallest element? He
The arrows show
the direction that
the trends
increase!!!
For each of the following descriptions, write a brief description of what each clue tells you, then identify the element
and write its electron configuration (you may use the shortcut).
39. Element #1
a. I tend to react by losing electrons.
b. I am an Alkali Metal.
Metal
Group 1A
c. I am not the smallest or the largest atom in my group.
d. I have a higher ionization energy than potassium.
e. I have a larger radius than lithium.
What element am I?
Na
Not H Not Fr
Above K
Below Li
My electron configuration:
1s2 2s2 2p6 3s1
40. Element #3
a. I have the greatest electron affinity in my period.
b. I have no “d” electrons
Right of period not a noble gas Group 7A
Above period 4
c. I have a higher ionization energy than bromine
Above Br
d. I do not have the greatest electron affinity in my group.
What element am I?
Cl
My electron configuration:
Not F
1s2 2s2 2p6 3s2 3p5
The arrows show
the direction that
the trends
increase!!!
41. Planets are constantly being explored using satellites and space probes. A fictional planet named Senecus
is investigated by scientists. Since the planet is so new, there are very few elements in existence, none as
heavy as our transition metal elements on earth. The periodic table for this fictional planet is developed
in a similar way to our real periodic table. In this fictional world, there are only 8 known elements. Using
the information found about each one, place them into the Senecus periodic table in the appropriate
locations. Assume that Senecus’ periodic table has the same trends as our real periodic table.
Senecus Periodic Table
1
2
3
C H G
F D E
A B







Elements G and E are unreactive and have full valence shells.
Element E has a larger radius than element G.
Elements A, C, and F are the most reactive metals. The atomic radius
for each of these elements is the largest in their periods.
Element C is determined to have the greatest electron affinity in the
group.
Element F has a higher ionization energy than element A.
Element D has the same number of energy levels as element E.
Element B has properties more like a metal, while element H has
properties more like a nonmetal.
42. Periodic Table Terms: Make sure you are familiar with, and can properly label the terms below on the blank periodic
chart.
Periodic table
group and family numbers
period
representative elements
transition elements
inner transition elements
metals
nonmetals
metalloids
alkali metals
alkaline earth metals
halogens
noble gases
lanthanide series
actinide series
SEE YOUR COLORED IN PERIODIC TABLE 