1) HW #9 PG 696 #43-48
2) Nuclear test on Thur. 3/3--check the study guide
3) Pi day coming up Mon. 3/14—sign ups tomorrow
Quark
Monday, February 29, 2016
Friday, February 26, 2016
HW #8 for 2/29
1) HW #8 pg. 695 #33-38
2) Pi day on Monday, March 14th--sign ups next week
3) Test next Wednesday
4) Composition books due next week
2) Pi day on Monday, March 14th--sign ups next week
3) Test next Wednesday
4) Composition books due next week
Wednesday, February 24, 2016
Tuesday, February 23, 2016
HW # 6 for 2/23
1)
HW #6: pg. 695 #27-30
Friday, February 19, 2016
Take Home Lab #3
Take Home Lab #3: Half-Life Simulation
Question: What is the half-life of a
simulated nuclear reaction?
Safety: Be careful with the scissors
and keep them out of the reach of small children.
Materials: copy of provided paper,
scissors, a box
Procedure: In this lab, you will
simulate the graphing of the half-life of a radioactive substance using slips
of paper. A half-life is defined as the time that it takes for half of a
radioactive material to decay into another substance. You will simulate this
process by flipping some papers and taking out all that are facing the same
direction and continuing. The papers with the symbol facing down represent
atoms that are radioactive. Those facing up have already decayed.
Cut out all the pieces of paper
with the Greek letter a
(Alpha) on them. Put them in a box and shake them up. Take out all the pieces
that have the a
facing up. Count and record how many are left. Shake the box again, and again
remove all of the pieces that have the a
facing up. Count and record how many are left. Continue this until no pieces
are left. Repeat this procedure one more time.
Data Table:
Trial number:
|
Number of papers left:
|
1
|
100
|
2
|
|
3
|
|
4
|
|
5
|
|
6
|
|
7
|
|
Prepare a graph with trial # on the x-axis
and the number of papers left on the y-axis.
Papers
left
Trial
#
Post-Lab Questions:
1. How many shakes did it take to get
rid of all the papers?
2. Use your graph to interpolate the
half-life if each shake represents 1,000 years.
3. Use your graph to answer the
question, “How many years have passed when 25% of the papers are left?”
4. According to your data, what is the
oldest object that this method could be used to date?
HW #5 for 2/22
1)
HW
#5: pg. 682 #1-2, 4, pg.
695 #21, 23-24
2) Take Home Lab #3 due Mon 2/22
3) Periodic Assessment Monday
2) Take Home Lab #3 due Mon 2/22
3) Periodic Assessment Monday
Wednesday, February 17, 2016
Pennies Half Life Lab
Pennies Half Life Lab
Background: Uranium-238
or U-238 is a radioactive isotope of the element uranium. Uranium-238 decays to lead-206, which is a
stable isotope of the element lead. The
half-life of uranium-238 is 4.5 billion years. So every 4.5 billion years, half
of the uranium-238 atoms in a sample will decay to lead-206. In other words, during any 4.5 billion year
period, the probability that a particular uranium-238 atom will decay is ½.
The
absolute age of a rock can be found by analyzing the rock for uranium-238 and
lead-206. Knowing the amounts of both of these isotopes enables scientists to
calculate how long ago the rock formed. In the following experiment, you will
use pennies to model radioactive decay.
Objectives:
1. To model radioactive decay using
pennies to represent uranium atoms.
2. To demonstrate the concept of
half-life and how it is used in radiometric dating.
Pre-Lab Questions:
1. Define the
term “half-life”.
2. What does
it mean when we say that an atom has “decayed”?
3. If you
start with 8,000 atoms how many will you have left after four half-lives? Show
your work.
4. If you
start with 1,920 atoms and now have 240 atoms left, how many half-lives have
past? Show your work.
Hypothesis:
1. Calculate
if you have ___ atoms, how many half-lives will it take until you have zero
atoms left.
2. How many
shakes do you think you will need to remove all your pennies from the box.
Procedure:
1. Place ____ pennies in your plastic
cup. Put your hand over the cup and
shake it several times.
2. Shake the pennies out into your
box until they are all flat on the box.
3. Remove all the pennies from the
box that are _____ side are turned upward.
4. Count how many pennies you removed
and how many pennies that you have left in the box. Record in the data table.
5.
Remove all the pennies from the box and place in the cup and shake out
again.
6. Repeat the steps again until there
are no pennies left in your container.
7. Repeat the steps again for a
second trial until there are no pennies left again and record your data.
Shake number:
|
Number of pennies remaining:
|
Number of pennies removed:
|
|||
Trial #1
|
Trial #2
|
Trial #1
|
Trial #2
|
Trial #1
|
Trial #2:
|
1
|
1
|
|
|
|
|
2
|
2
|
|
|
|
|
3
|
3
|
|
|
|
|
4
|
4
|
|
|
|
|
5
|
5
|
|
|
|
|
6
|
6
|
|
|
|
|
7
|
7
|
|
|
|
|
Analyzing your results:
1. Use the graph data example on the
screen to graph your results.
2. Make sure to label your axes on
your graph.
3. Graph trial #1 and trial #2 on
your graph with two different colors.
4. Draw a smooth line/curve to
connect your points for each of your trials.
5. Write your results on the class
data sheet at the front of the room.
Post-lab questions:
1. Examine the half-life of uranium-238 graph on
the screen and the graph you have made.
Does the lines/curves have the same shape? Explain why or why not.
2. Assume that
the pennies represent uranium-238 and lead-206 isotopes. Remember that
uranium-238 is the parent isotope and decays to lead-206 the daughter
isotope. In this model, which isotope
represents the “head” side of the penny? Which isotope represents the “tail”
side of the penny?
3. If a
“sample” of pennies had 75 heads and 25 tails showing, how many half-lives
would have passed since the “sample” had formed and begun to decay? (Hint: the original sample had 100 tails.
Which each half-life, half of the pennies became heads. How many half-lives does it take to get to 75
heads?)
4. Do you think
the number of pennies (or atoms) you start with affect the outcome? Explain.
5. Describe
the shape of the line/curve you made with your graph. What does that shape tell you about the
results?
HW #4 for 2/18
1)
HW #4:
pg. 694 #12 b-c, 14-18
2) Test make up due Fri. 2/19
2) Test make up due Fri. 2/19
Friday, February 12, 2016
HW #3 for 2/16
1) HW #3 pg. 673 exer 19.1 (yellow box), pg. 674 exer 19.2 (yellow box), pg 678 #3, pg. 694 #12
2) Test make ups due on Friday, February 19th. Write out corrections SHOWING work on a separate piece of paper and staple to your original test.
2) Test make ups due on Friday, February 19th. Write out corrections SHOWING work on a separate piece of paper and staple to your original test.
Thursday, February 11, 2016
Reading Questions for Sec 19.1
Section 19.1: Reading Questions (pg. 668-677) on pg. 39
1. It states in your text that there are about 2000
nuclides known. How can this be possible if there are only about 100 elements?
2. Write the charge, mass number, and symbol for a
beta particle and an alpha particle.
3. By how many units does the mass number of a nucleus
change when the nucleus produces an alpha particle? By how many units does the mass number of a
nucleus change when the atom produces a beta particle? Is each change an increase or a decrease in
mass number?
4. Draw what it looks like
when a beta particle leaves the nucleus.
Draw what it looks like when
an alpha particle leaves the atom.
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