Name ________________________________________
Weekly 2, Due ________________________________.
I will grade this and give it back to you, then you will have a short quiz on a few of the
topics covered on this review. The questions may be different, but if you understand how
to do these questions, then you will be well prepared for the quiz.
I would be more than happy to help you on this graded homework assignment, but since
this is review, I need to see that you put in some effort. If you come to ask me questions,
you must show me the section in your notes that you have looked at to help you answer
it. If you come for help you must bring your reference table and your calculator.
1. The atomic mass of an element is defined as the weighted average mass of that
element’s ___________________________.
2. A. Define isotope in your own words:
B. Element X has two isotopes. If 72% of the element has an isotopic mass of
84.9 amu and 28% has an isotopic mass of 87.0 amu, the average atomic mass
of Element X is ________________________
Show work here:
3. Complete the following chart:
Symbol
Atomic Number
H
Mass Number
3
Number of
neutrons
Number of
electrons
U
19
238
20
4. Ernest Rutherford performed an experiment in which _____________ particles
were aimed at ______________ foil. When a few of the particles bounced back
instead of passing through with little or no deflection, Rutherford is quoted as
saying, “I was as surprised as if I had aimed a 14-inch artillery shell at a piece of
paper and it bounced back.” Why was he so surprised, and how did he modify the
model of the atom to explain his result?
5. Draw the atomic model of the following:
N
Na
Ca
6. Record this measurement to the correct number of sig figs.
________ cm
1 2 3 4 5 6 7 8 9 10 11 12
7. How many significant figures are in each of the following numbers?
a. 203
b. 12,700
c. 7,720.
d. 0.003
e. 0.460
8. Complete the following mathematical operations and round to the correct number
of significant figures.
a. 12.0 x 3.0
b. 23.1 + 6.58
c.0.40 + 1.32
d.6.5 ÷ 2.512
9. Complete the following table regarding the measurements:
Measurement (cm)
List known digits, if any
List uncertain digits, if any
# of significant figures
29.7
0.02310
160
10. Perform the following calculations, round your answer to the correct number of
significant figures:
7.20 x 10-5 / 1.21 x 10-2 = ________________________________________
4.68 x 1014 * 8.9031 x 1010 = _____________________________________