Transcript Vocabulary Week 6 - Brookwood High School

Are your parents/guardians coming
to open house tonight?
A. Yes
B. No
Vocabulary Week 6
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atomic number
atomic mass
alpha radiation
gamma radiation
isotope
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cavil
charlatan
ebullient
ambient
eclectic
Atomic number is the _____ number
and it tells how many ______.
a. bottom, protons + neutrons
b. bottom, protons
c. top, protons + neutrons
d. top, protons
An isotope is an atom with the
same number of _______ but a
different number of ________.
a.
b.
c.
d.
neutrons, protons
protons, neutrons
protons, electrons
electrons, protons
Review
• Calculate the atomic mass
1H
12%
2H
48%
3H
40%
%1
%2
Weighted Average  (
 amu1)  (
 amu 2)  ...
100
100
Nuclear reactions involve changes
in an atom’s ___________ while
chemical reactions involve changes
with _________________.
a. nucleus, electrons
b. electrons, nucleus
Radioactivity
• Chemical reaction involves only an
atom’s electrons – the nucleus remains
unchanged
• Nuclear reaction involves a change in an
atom’s nucleus (p+ or n0)
• Radioactivity is when substances
spontaneously emit radiation
• The rays and particles emitted are
radiation
The reason why atoms undergo
radioactive decay is to become
unstable.
a. True
b. False
Radioactivity
• When there are too many protons vs neutrons,
the positive charges will repel each other causing
the atom to be unstable
• Unstable  radioactive decay  stable
•   radioactive decay  
The following show the correct
order of strength of radiation from
strongest to weakest.
a.
b.
c.
d.
alpha, gamma, beta
alpha, beta, gamma
gamma, beta, alpha
gamma, alpha, beta
Nuclear Reactions
• Alpha Radiation
–α
4
2
He
2 protons & 2 neutrons
– Can be stopped with paper (tissue paper)
241
95
Am Np  He
237
93
241 = 237 + 4
95 = 93 +2
4
2
Nuclear Reactions
•Beta Radiation
–ß
0
1

– negative charge
– Fast moving electron
– Can be stopped with foil (think aluminum foil)
C N  
14
6
14
7
14 = 14 + 0
6 = 7 + -1
0
1
Nuclear Reactions
• Gamma Radiation
0
0
– Energy released from breaking bonds in nucleus
– Occurs with α or ß radiation
– Can be stopped with lead or concrete
U  Th  He  
238
92
234
90
4
2
238 = 234 + 4 + 0
92 = 90 + 2 + 0
0
0

• Conversion of an atom of one
element to an atom of another
element is called transmutation.
Half Life- pg 817
• Time it takes for ½ of radioisotope’s nuclei
to decay
• Each element has a unique half life
– Polonium-214 = 163.7 microseconds
– Radon-222 = 3.8 days
– Carbon-14 = 5730 years
– Uranium-238 = 4,460,000,000 years
Half Life
• Either memorize formula OR
– Amount remaining = initial amount x (½ )n
• Where n is the number of half lives that passed
– Amount remaining = initial amount x (1/2)t/T
• t = elapsed time, T = duration of half life (must
be in same units!)
•Draw Pictures
1. The carbon-14 in a sample of bone has ¼ of
its original amount. How old is the bone?
(Carbon-14 has a half-life of 5730 years)
2. Only 1/8th of the original dose of radon-222
remains in a test subject. How long ago was
the radon introduced into the test subject’s
body? (Radon-222 has a half-life of 3.8 days)
3. Barium-139 has a half-life of 43 minutes.
How many hours will it take to degrade to
1/32nd of its original amount?
4. Polonium-211 has a half-life of 3.2 days. How
long will it take to degrade to 1/128th of its
original amount?
5. Cobalt - 60 is used to detect leaks in water
lines. It has a half life of 38 hours. It can not
be detected by the sensors after it reaches
1/32 of its original amount. How many days do
engineers have to test the water lines before
the Cobalt –60 is undetectable?
Gas prices keep going up, up, and up….
• The problem now is that cars have to be
plug in everyday
Nuclear Fission
• Process of one atom breaking down into
smaller atoms
• http://lectureonline.cl.msu.edu/~mmp/appli
st/chain/chain.htm
• Biggest problem with nuclear power is
the nuclear waste
• Currently, the depleted uranium is stored
underground in Yuma, Arizona.
Nuclear Fusion
• Fusion is the process of combining 2 smaller
atoms into one larger atom
• Produces 10 times more energy than fission
• No nuclear waste! 
Recap…
• Radiation Penetration
• Fission
– Alpha α
– Beta ß
– Gamma γ
• Nuclear power
– Biggest problem?
• Waste disposal or nuclear
meltdown?
• Fusion