Regents Chemistry Lab # 3
Name: _____________________________
Role: ______________
2014-15
period: _______ due date: _________________
RUBRIC
Section 1:_______/10
Section 2:_______/2
The Radioactive Decay of Uranium-238
Section 3:________/8
__________________/20
23892U
23490Th
Pre-lab Questions:
1. Explain how unstable atoms gain stability.
2. What determines whether or not an atom is stable?
3. What is the process whereby an atom gains stability called?
4. What is a radioactive decay series?
5. When balancing a nuclear equation, what two quantities are
conserved?
6. If a scientist wishes to determine the age of Earth, the scientists would
need to compare the relative amounts of which two isotopes.
7. Why is U-235 used for nuclear power and weapons instead of U-238?
8. HALF – LIFE PROBLEM:
Uranium-238 decays very
slowly, w/ a half-life of 4.47
billion years. What fraction
of a sample of uranium -238
would remain after 13.4
billion years?
SECTION 2: write the 14 equations that represent the natural radioactive decay of U-238 to Pb-206
TO BE HANDWRITTEN ONLY! Use this page only if need to re-write your equations
1.__________ 23892U 
42He
+
23490Th
[note: isotope product becomes reactant of next decay rxn]
2.
____23490Th_ 
______
3.
________
_______
4.
________
_______
5.
________
_______
6.
________
_______
7.
________
_______
8.
________
_______
9.
________
_______
10.
________
________
11.
________
________
12.
________
________
13.
________
________
14.
________
________
NOTE: The nuclear equations
for section 2 SHOULD be
written by hand but MUST be
neat & legible to receive full
credit!
Write one example each that illustrates an alpha and a beta decay equation from the equations above
Alpha decay:
Beta decay:
`