Download Honors Review Unit 2 answers

Test Review
Chapters 4 and 25
Honors Chemistry
Answers
1. Fill in the blank with the name of the historical person associated with the reference. Some names will
be used more than once.
James Chadwick
John Dalton
Democritos
Eugene Goldstein
Antoine Lavoisier
Robert Millikan
Ernst Rutherford
JJ Thomson
Used the famous “gold foil” experiment. ____Rutherford__________
Discovered the proton _____Goldstein__________
Discovered the charged nucleus (small) is the center with 99.9% of the atom as empty space where the
electrons reside. ______Rutherford_______
Used an “oil drop” experiment to discover the charge and mass of an electron. ___Millikan__
Proposed the “Plum Pudding” model of the atom. _____Thomson________
Used the word “atomos” to describe matter. _____Democritos________
Called the “Father of Modern Chemistry”. ___Lavoisier_________
Discovered the neutron. _____Chadwick___________
Created the first atomic theory based on experimental evidence. _______Dalton_______
Discovered the electron. ______Thomson________
Discovered the nucleus. ____Rutherford_________
Discovered the Law of Conservation of Mass. ____Lavoisier_________
Proposed a model of the atom as a hard, indivisible sphere. _____Dalton______
Conducted experiments with cathode rays. ____Thomson_________
Know the 5 points of Dalton’s atomic theory and how two of those points have been changed!
1. All matter is made of atoms.
2. All atoms of the same element are exactly the same. Atoms of different elements are different. CHANGE – ATOMS OF THE SAME
ELEMENT CAN HAVE DIFFERENT MASSES (ISOTOPES)
3. Atoms are indivisible. CHANGE – SUBATOMIC PARTICLES (PROTONS, NEUTRONS, ELECTRONS)
4. Atoms of different elements combine in whole number ratios to form compounds.
5. In chemical reactions, atoms are either combined, separated, or rearranged.
2. Fill in the following chart for the isotopes:
Isotope Name
Atomic
Number
(Z)
Mass
Number
(A)
Number
of
protons
Number
of
neutrons
Number
of
electrons
25
55
25
30
21
62
155
62
93
62
Sb
51
121
51
70
51
O-2
8
18
8
10
10
Symbol
Manganese – 55
55
25
Mn+4
Samarium – 155
155
Antimony – 121
121
Oxide – 18
18
62
Sm
51
8
3. The most common isotopes of chromium are listed below. What is the average atomic mass of
chromium? 52.02 amu
Isotope
Chromium – 50
Chromium – 52
Chromium – 53
Chromium – 54
Mass (amu)
49.9460
51.9405
52.9406
54.0022
Percent Abundance
4.55%
81.75%
9.81%
3.89%
85
87
4. Element X is a soft, silvery-white metal that has two common isotopes, X and X. If the abundance
85
87
of X is 72.2% and the abundance of X is 27.8%, what is the average atomic mass of X? What is
element X? 85.6 amu, Rb
5. Silicon has three naturally occurring isotopes. What is the average atomic mass of silicon? 28.09 amu
Isotope Name
Silicon-28
Silicon-29
Silicon-30
Isotope Mass (amu)
27.98
28.98
29.97
Relative Abundance (%)
92.21
4.70
3.09
6. How many atoms is 0.00556 moles of barium? 3.35 x 1021 atoms
7. What is the mass of 0.44 moles of carbon? 5.3 g
8. How many atoms does 43.25 g of iron contain? 4.662 x 1023 atoms
9. If a student weighs out 2.01 g of silicon, how many moles is that? 0.0716 moles
10. How many moles are there in 2.4010 x 1025 particles of gold? 39.884 moles
11. What is the mass of a block of aluminum that has a volume of 22.4 cm3? (Density of Al = 2.70 g/cm3)
60.5 g
12. If a metal cylinder of copper (density = 8.9 g/cm3) has a mass of 45.4 grams, what is the volume of
the cylinder? 5.1 cm3 What is the cylinder’s diameter if it is 1.2 cm in height? 1.2 cm
13. Convert 2950 micrograms to kilograms. 2.95 x 10-6 kg
14. Change 0.00014 hectoliters to nanoliters. 1.4 x 107 nL
15. Write the symbols for an alpha particle, beta particle, and gamma ray. Alpha particle – 42He;
-1
0ß;
Beta particle -
Gamma particle – 00γ
16. When a nuclei undergoes alpha decay, how does the mass number change? Decreases by 4
17. During beta decay, describe what happens to the atomic number of the element. Increases by 1
18. What is the most penetrating form of radioactive particles? What can stop this form of radioactivity?
Gamma rays, several meters of concrete or several centimeters of lead does not fully stop it
19. Write the equations for the reaction when the following undergo alpha decay:
a. 235U
b. 241Am
c. 212At
d. seaborgium-263 (Sg)
92
a.
235
95
4
U
92
c.
212
He +
231
2
4
At
85
Th
85
b.
90
4
Am
95
He + 208Bi
2
241
d.
83
263
He + 237Np
2
4
Sg
106
93
He + 259Rf
2
104
20. Write the equations for the reactions when the following undergo beta decay:
a. 66Cu
b. 84Br
c. oxygen-18
d.
29
a.
66
35
0
Cu
29
c.
18
B + 66Zn
-1
0
O
8
96
b.
30
84
d.
9
0
B + 84Kr
-1
36
Br
35
B + 18F
-1
244
0
Cm
96
B + 244 Bk
-1
97
21. Write the equation showing the following isotopes undergoing gamma decay:
a. Radium-218 (Ra)
a.
γ + 218Ra
218
0
88
0
Ra
88
244
b. Uranium-239 (U)
b.
239
U
92
γ + 239U
0
0
92
Cm
22. If the half-life for the radioactive decay of zirconium-84 is 26 minutes and I start with a 175 gram
sample, how much will be left over after 104 minutes? 10.9 g
23. Mercury -197 is used for kidney scans and has a half-life of 3 days. If the amount of mercury-197
needed for a study is 1.0 gram and the time allowed for shipment is 15 days, how much mercury-197 will
need to be ordered? 32 g
24. How much strontium-90 will remain after 4 half-lives if the initial amount is 4.0 g? 0.25 g
25. Iodine-131 is used to destroy thyroid tissue in the treatment of an overactive thyroid. The half-life of
iodine-131 is 8 days. If a hospital receives a shipment of 550. g of iodine-131, how much I-131 would
remain after 60 days? 3.04 g