Atomic Structure/Nuclear Chemistry Unit Test Review
Name______period ______- date______
1. Cobalt-60 has a half life of 5.3 year. Starting with 10.0 g of this isotope, how many grams will
remain after 21.2 years?
2. Calculate the weighted average atomic mass of potassium:
Isotope: Abundance (%): Mass(g):
K-39 93.12 38.964
K-41 6.88 40.962
3. Identify each of the following as nuclear changes or chemical changes:
. A. 131I ® 131Xe + 0e-
B. 2KClO3 ® 2KCl + 3O2
C. H2CO3 ® H2O + CO2
D. 226Ra ® 222Rn + 4He
4. Which type of reaction (nuclear or chemical)
A, is affected by environmental conditions such as temp, pressure, etc.
B. releases the greatest amount of energy?
C. results in a new element
5. What happens to the nucleus of a radioisotope during fission? During fusion?
6. Compare the laws of definite proportions and multiple proportions.
7. Which subatomic particle is responsible for
A. the identity of the element –
B. the chemical reactivity of the element –
C. the electrical charge of the element’s ion -
8. Match the atomic model with the name of the man who developed it:
_____ “Plum pudding” A. Schroedinger
_____ Probable location of
electrons in cloud B. Bohr
_____ Centrally located nucleus
with positive charge/atom is
mostly empty space C. Thomson
_____ Concentric rings (energy levels)
around the nucleus D. Rutherford
E. Dalton
9. Write the 5 postulates of Dalton’s atomic theory:
10. Which of the following BEST illustrates the law of multiple proportions:
A. HCl and HNO3 B. CO and CO2 C. NaCl and NaClO3 D. H2SO4 and CuSO4
11. For these isotopic symbols: 65Zn+2 31P-3 How many protons, neutrons and electrons do they
each have? 30 15
12. What is the unit of mass for the subatomic particles (and the atom itself)?
13. Write a balanced nuclear equation for
a. the alpha decay of Americium – 241.
b. the beta decay of Cesium – 137.
14. Define half life:
15. Which of the following nuclear processes will result in an atom with a higher mass number?
A. alpha decay
B. beta decay
C. gamma decay
D. nuclear fusion
16. Which of the following nuclear processes will result in an atom with a lower atomic number?
A. alpha decay
B. beta decay
C. gamma decay
D. nuclear fusion
17. Complete this chart:
Subatomic particle electric charge location in atom
(+, --- , 0)
18. An particle has 9 protons, 10 neutrons and 10 electrons. What is the net charge on the particle?
Matching:
______19. All atoms of an element have the same A. Neutrons
number of these particles.
B. Protons
______20. Isotopes have different numbers of these
particles in their nucleus. C. Electrons
______21. Only these particles are involved in chemical
changes
Matching: (Continued – A. neutrons B. protons C. electrons
______22. The atomic number of an element is made of
these.
______23. The atomic mass is the sum of the protons and
these particles.
______24. These particles determine the identity of the element.
______25. An atom of Mg has a mass of 24 while another atom of Mg
has a mass of 25. The difference in the mass of these 2 atoms
is due to a different number of these particles.
Look at these symbols of elements (with the atomic mass and atomic number):
24W48 24X50 24Y51 24Z53
26. Of these 4 elements, which has an equal number of neutrons and protons? ______
27. Of these 4 elements, which has the greatest number of neutrons? ______
28. Which of these elements are isotopes of the same element? ______
29. What is the atomic number of element W? ______
30. What is the identity of the element(s)? ______
31. Plutonium-239 (Pu-239) has a half-life of 24,000 years. How long would it take for a 100.0 g
sample of Pu-239 to decay to 25.0 g?
A. 12,000 years
B. 24,000 years
C. 48,000 years
D. 72,000 years
32. Copper has two isotopes: Cu-63 (present in 69.2% with a mass of 62.930 amu) and Cu-65 (present in
30.8% with a mass of 64.928 amu). Calculate the atomic mass of Copper. (Show all work, no naked
numbers and circle final answer).
33. Nitrogen has two naturally occurring isotopes: N-14 and N-15. The atomic mass of Nitrogen is
14.007 amu. Which isotope is present in the greater amount? Explain your answer.