Bellwork 9-24-2014
1. What are 4 components required for a nuclear
reactor to power a town (produce electricity)?
**Tests will be returned Thu/Fri
Agenda
Bellwork
Build your own nuclear reactor
Exit slip
Homework
Nuclear Reactors
You have the following materials at your disposal:
Beaker of water
Straw
Hot plate
Aluminum foil
Windmill
Cork if you need
to stopper your
windmill
Build it!
Use your knowledge from the nuclear reactor video
to build a nuclear reactor that will power your
windmill!
When you are done, answer the following
questions about your reactor:
1. How did you make your nuclear reactor work?
Give a description of how you built your device.
2. What specific components were needed to
maximize efficiency?
Clean Up
I will take the beaker off the hot plate with a hot
hand
Take out straws and leave on desk
IF you used the tin foil, unwrap it for the next
class
Set everything back in the center when your are
done
CAUTION – HOT PLATES ARE STILL HOT!
Exit Slip
Stamped questions from nuclear reactor
building lab
Homework
Reading on radiation
Highlight important information
Annotate:
Each section – write a mini one sentence
summary on the article itself next to the
appropriate section
10 sentences total
Example
First paragraph:
Radioactivity is the emission of particles
or from unstable atoms and can be
natural or induced.
Bellwork 9-25-2014
Form your article:
1. What is radioactivity?
2. Describe alpha particle radiation.
3. What two main isotopes are released into the
atmosphere from burning coal?
**Pass back tests
Announcements
Points – class monitor
Extra credit drawing
Tutoring Friday is ON!
Why is
36Cl
Unstable?
Unstable
Nuclear Strong Force
Mysterious force holding nucleus (protons and
neutrons) together
Student Demo
Everyone up!
4 students start in the center of the desks –
this is our NUCLEUS
Question:
• What happened when too many students were
added to the “nucleus”
What makes an atom
unstable?
Nuclear strong force fails
Too many neutrons or too many protons
Stability is based on a specific ratio of
protons to neutrons in the nucleus
In nature, 92 p+ MAX  Uranium
Why do we call these atoms
unstable?
Atoms like 36Cl are radioactive elements
They break down or DECAY at a specific rate
and give off RADIATION
Nuclear Radiation
Nuclear radiation is the process during which
the nucleus of an unstable atom spontaneously
breaks down in
an attempt to
form a more
stable nucleus.
This process
emits
RADIATION
What is radiation?
Waves traveling through space at
specific wavelengths
Examples:
• Natural radiation from the sun
• High energy radiation from space,
air or the earth
• Background radiation – main
source (alpha, beta, gamma)
Share with your neighbor
Write down your answer
1. What is the nuclear strong force?
2. What types of atoms overcome this force?
3. What happens when atoms overcome this force?
Nuclear Decay
The rate at which an element breaks down into
a daughter element
This is calculated using half lives
t1/2
Half life: how does it work?
1. What happened after the first half life?
2. What happened after the second?
Graphical form
Half Life
The amount of time it takes for an
element to decay to HALF of its original
amount
For example:
Chlorine-36 will
decay to half of its
original amount in
301,000 years
How is it measured?
Half life can be determined using any amount
of the substance that can be measured:
Mass – grams
Protons
Neutrons
Practice with a neighbor
1. 50 grams of Chlorine-36 has a half life of
301,000 years, how much will be left after 1
half life?
2. How much will be left after
2 half lives?
**You will need a calculator!
Half Life Problem 1
200 grams of Bismoth-214 has a half life of 20
minutes. Fill in the table to determine how
much is left after 4 half lives.
Time passed (min)
Half life
0
0
1
2
3
4
Amount remaining
(g)
Half Life Problem 2
After 135 days, you have 8 protons of Iron-59
left. This element has a half life of 45 days. How
much did you start with?
Time passed (min)
Half life
0
0
Amount remaining
(P+)
On your own…
Work on the half life problems on your
worksheet independently
This is partner work = voice level 2, if you are
too chatty you will be moved or asked to
leave.
You have 20 minutes to complete this for a
stamp
Exit Slip 9-25-2014
Describe WHY elements have half lives
and WHAT half life is in your own words
using key vocabulary from today:
The WHY:
Nuclear strong force
Radioactivity
Radiation
Unstable
Isotopes
The WHAT:
- Radioactive elements
- Half
- Decay
- P+, n0, mass
Work Collection
Bellwork separate
1. Nuclear reactor video questions
2. Exit slip – questions from nuclear reactor lab
3. Radioactivity article
4. Lab sheet from today
5. Exit slip from today
Bellwork 9-30-2014
1. What types of atoms decay according to their half lives? What
do they give off during this process?
2. If 130 grams of radioactive Carbon-14 has a half life of 5,730
years, how much will be left after 3 half lives? How much time
has passed?
Time passed (min)
Half life
0
0
1
2
3
Amount remaining (g)
Homework Answers
1 = 25g left
2 = 25 p+ left
3 = 75 n left
4 = started with 64 g
Announcements
Volunteers?
•
Class ambassador
•
Class monitor
•
Class tutors
Test corrections due next Mon/Tue, Oct 6/7
Tests have been posted online
If you missed the test you will be required to do test corrections
for the whole test in order to raise your 0 to a 3.
Test Correction Reminder
FOR EACH QUESTION YOU GOT WRONG:
1. EXPLAIN: why you got the question
wrong
2. WRITE: the correct answer or solution
3. EXPLAIN: why that answer is correct
Half Life Activity
Period 2, 4, 5(graph)
In groups of 4 – you will need a paper
plate and a lab sheet
1. Follow the procedures on your lab sheet
2. Graph your data using appropriate graph
labels:
a. Title
b. X and Y axis labels
c. Appropriate scale
3. You have 20 minutes to complete for a stamp
Honors: Another way…
Half life can also be calculated using an equation:
A=
t/h
A0(1/2)
A = amount remaining
A0 = initial amount
t = time
h = half life of the isotope
Oder of surgeries… I mean
operations…
4 easy steps:
Step 1: Plug in the numbers
Step 2: divide the exponent
**Exponent values must ALWAYS be in the same
units
Step 3: raise ½ to the power (quotient of step 1)
Step 4: Multiply
Do it…
Example 1:
50 grams of Bismoth-214 has a half life of 20
minutes. Use the equation to determine how much is
left after 200 minutes.
A = A0(1/2)t/h
A = 50 (1/2) 200/20
A = 50 (1/2) 10
A = 50 (0.00097)
A = 0.05 g
Honors: Practice Problems
Do the first 2 practice problems from the worksheet on
separate sheet of paper (homework).
Objective:
Students will be able to create and write
balanced chemical equations for alpha, beta
and gamma decay.
http://www.youtube.com/watch?v=Zw0pHT4
7AAU
What is a balanced equation?
In terms of radioactive decay:
• Both sides of the equation arrow have the
same TOTAL mass and number of protons.
Interesting Fact
Alpha, beta and gamma decay are
responsible for supplying HALF of
the Earth’s natural heat
Alpha Decay
Alpha decay is one of
the ways unstable
elements emit radiation
in an attempt to
become more stable
Alpha Decay Simulation
On your worksheet is the website you will
visit for this simulation
Complete ONE worksheet per pair
You have 20 minutes
Alpha Decay – Exit Slip
5 minutes: In your notes:
Describe alpha decay. On a half sheet of paper
1.
What element is emitted and what subatomic particles does it consist of?
Helium – 2p+ and 2n0
2.
How do you determine the new element produced? Subtract 2 protons
(move two to the left on the periodic table)
3.
Give an example: Write the alpha decay of Uranium – 235.
Thorium – 231
Helium - 4
Uranium-235  _____________
+ _______________
231
4
235
90 Th
2 He
92 U _________
+ _________
Bellwork: Honors 8-1-2014
Use the half life decay equation to solve the following problem:
A = A0(1/2)t/h
1. Thorium-228 has a half life of 1.9 years. How much Thorium
did you START with if only 3 grams remain after 38 years?
2. Thorium-234  ___________ + _____________
234
90 Th
 ________ + ________
Bellwork 8-1-2014
1. Complete the following equation using alpha decay in HYPHEN
notation and SYMBOL notation
Thorium-234  ___________ + _____________
234
90 Th
 ________ + ________
2. Period 6: Use the product from alpha decay in the pervious
reaction and put it through beta decay (Hint: not the helium atom!)
__________  ___________ + ____________
Announcements
Test corrections due next Mon/Tue
I am allowing everyone to correct the first test but in the future
I will not giving credit to students who do test corrects with a
formative grade <2.7
Grade are posted on the back wall – check as you leave
I will be holding individual conferences with students today
while you work
Homework quizzes
Agenda
Bellwork (10 minutes)
Beta Decay (20 minutes total)
Beta Decay debrief (5 minutes)
Gamma Decay notes (10 minutes)
Exit slip – review all three types of decay (5 minutes)
If time – posters on one form of decay to display in the room
(extra credit)
Beta Decay
Beta decay is another
way that unstable
elements emit radiation
in an attempt to
become more stable
Beta Decay Simulation
On the backside of your worksheet is the
website you will visit for this simulation
Complete ONE worksheet per pair
You have 20 minutes
Beta Decay – Debrief
5 minutes: In your notes:
Describe beta decay.
1.
What particles are emitted during this type of decay?
2.
A _________ changes into a ____________.
3.
How do you determine the new element produced?
4.
Give an example: Write the beta decay of Uranium – 235.
Uranium-235  _____________ + _______________
235
92 U  _________ + _________
Gamma Decay
Gamma decay is the last
Form of decay we will
talk about where
unstable atoms emit
waves in an attempt to
become more stable.
No simulation 
Gamma Decay:
https://www.youtube.com/watch?v=5U3YVW8Fk-M
In your notes:
Describe gamma decay. What is given off and how do
you determine the stable element produced?
1.
Give an example: Write the gamma decay of Uranium – 235.
Uranium-235  _____________ + _______________
235
92
 _________ + _________
With a partner…
Make a poster of your own rendition of alpha,
beta or gamma decay that would be easy to
understand by someone who has NEVER
learned the subject.
Include:
What is emitted and what it consists of
How mass and # of protons change
How you determine the new element produced
An example of the decay used in an equation
(HINT: this can be used to hit the other points)
Homework 8-1-2014
Finish the packet on alpha, beta and
gamma decay by Thursday/Friday
Homework quiz Thu/Fri – bellwork
Exit Slip 8-1-2014
Fill in the blanks:
1. Alpha decay radiation emits an ________ particle that is also called
_________. This element consists of ____ protons and ____
neutrons. The daughter element produced has _____ less protons and
its mass is reduced by ______.
2. Beta decay radiation emits an ________ with a mass of ______ and
a atomic (proton) number of ________. A _______ is changed into a
__________ in the process. The daughter element produced has
______ more proton and the ________ mass.
3. Gamma decay radiation emits __________ that have a mass of
_____ and _____ protons. The daughter element produced is ______.