Transcript Atomic Energy

Atomic Energy
Atomic Energy
Agenda
1.What do you know
about radiation?
2.Intro to atomic
energy
3.Let’s read up on it!
4.Watch your
“headsium”.
5.Alpha, Beta, Gamma
6.Project
Warm-up:
What do you know about radiation?
Homework: Reread pages 80-87.
OBJ 1: Compare alpha, beta, and
gamma decay
Nuclear Power
http://environment.nationalgeographic.com/enviro
nment/energy/great-energy-challenge/nuclearpower-quiz/
Nuclear Radiation
high-energy particles and rays that are emitted by
the nuclei of some atoms
radioactivity: the ability to give off nuclear
radiation
History!!
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http://www.neok12.com/Nuclear-Power.htm
3 different types of radiation.
Nuclear radiation is produced
through decay
Radioactive decay- the process in which the
nucleus of a radioactive atom releases nuclear
radiation
3 types of decay:
alpha
beta
gamma
Alpha Decay
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Release of an alpha particle from a nucleus
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Alpha particle = 2 protons and 2 neutrons; has
a mass of 4 and charge of 2+ (is identical to
nucleus of a helium atom) *Large radioactive nuclei give off
alpha particles to become nuclei of atoms of different elements.
Reminder
mass number = ___ + ___
Radium - 226
atomic number =
proton number =
neutron number =
electron number =
Conservation
sum of mass number of starting material = sum of
mass number of products
charge is conserved . . .sum of charges of starting
is always equal to sum of charges of products
Radium-226 undergoes
alpha decay
the decay
Radium 226 ----> Radon 222
Charge 88+ ----> Charge 86+
into 2 products
He - 4
Charge- 2+
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Americium- Atomic Number : 95
Neptunium- Atomic Number: 93
Alpha Particle: 2 protons & 2 neutrons
Beta Decay
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Release of a beta particle from a nucleus.
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Beta particle = an electron (having a charge of
1- and mass of almost 0) OR a positron (having
a charge of 1+ and a mass of almost 0). *Because
electrons and positrons do NOT contain protons or neutrons, mass number is 0.
two types of beta decay
A proton breaks down into a positron (1+) & a
neutron
Neutron breaks down into a proton & an electron
So if there’s 1 more proton in the nucleus…
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Beta decay occurs when the neutron to proton
ratio is too great in the nucleus and causes
instability. In basic beta decay, a neutron is turned
into a proton and an electron. The electron is then
emitted. Here's a diagram of beta decay with
hydrogen-3:
(taken from
http://library.thinkquest.org/3471/radiation_types_
body.html)
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There is also positron emission when the
neutron to proton ratio is too small. A proton turns
into a neutron and a positron and the postiron is
emitted. A positron is basically a positively
charged electron. Here's a diagram of positron
emission with carbon-11:
Gamma Decay
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Release of gamma rays from a nucleus. Occurs
after alpha or beta decay as particles shift in
nucleus to a more stable position. *Gamma rays alone do not
cause one element to change into another.
Gamma Decay
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The release of gamma rays from the nucleus
Energy that is released during alpha or beta decay
in the form of gamma rays
No mass
No charge
(Which is why it can penetrate
through many things except…
Does not cause 1 element to change into another
like alpha & beta
Watch Your “Headsium”
page 79 in book.
follow the instructions.
you will need graph paper
Please copy the following
Trials
Number of “headsium” nuclei remaining
0
100
1
2
3
4
5
6
7
8
Atomic Energy
Agenda
1. Let’s watch!
2. Gamma decay
3. Watch your “headsium”.
•OBJ 1: Compare alpha, beta, and gamma
decay.
•OBJ 2: Describe the penetrating power of
the 3 types of nuclear radiation.
•OBJ 3: Identify uses of radiation.
•Warm-up: Take several minutes and
complete the Section Review on page 84.
•Homework: Read and take notes on pages
84-87.
3 different types of radiation: What does this mean?
Alpha (α): could barely pass through a single sheet of paper. Deflected
as a positive particle in a magnetic field.
Beta (β): can pass through about 3mm of aluminum. Deflected as a
negative particle in a magnetic field.
Gamma (γ): can pass through several centimeters of LEAD! Not
deflected in a magnetic field.
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Some more history!
Wilhelm Conrad Roentgen (1845-1923) Drawn to
a glowing fluorescent screen on a nearby table. He determined
that the fluorescence was caused by invisible rays originating
from the partially evacuated glass tube he was using to study
cathode rays (i.e., electrons). Surprisingly, these mysterious rays
penetrated the opaque black paper wrapped around the tube.
Roentgen had discovered X rays!
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Antoine Henri Becquerel (1852-1908) Becquerel
chose to work with was potassium uranyl sulfate,, which he
exposed to sunlight and placed on photographic plates wrapped
in black paper. When developed, the plates revealed an image of
the uranium crystals. Becquerel initially concluded "that the
phosphorescent substance in question emits radiation which
penetrates paper opaque to light.“ He believed this was due to
the presence of the sun's energy which was being absorbed by
the uranium which then emitted X rays. Further investigation,
revealed that X rays were emitted without the presence of the
sun. Thus Becquerel had discovered radioactivity, the
spontaneous emission of radiation by a material.
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Pierre Curie (1859-1906) Marie Curie (18671934) Together, they began investigating the phenomenon of
radioactivity recently discovered in uranium ore. Although the
phenomenon was discovered by Henri Becquerel, the term
radioactivity was coined by Marie. After chemical extraction of
uranium from the ore, Marie noted the residual material to be
more "active" than the pure uranium. She concluded that the ore
contained, in addition to uranium, new elements that were also
radioactive. This led to their discoveries of the elements of
polonium and radium, but it took four more years of processing
tons of ore under oppressive conditions to isolate enough of
each element to determine its chemical properties.
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Ernest Rutherford (1871-1937) Named and
characterized the alpha particle, beta particle and proton. Even
the neutron, discovered by James Chadwick, owes its name to
Rutherford. The exponential equation used to calculate the
decay of radioactive substances was first employed for that
purpose by Rutherford and he was the first to elucidate the
related concepts of the half-life and decay constant. With
Frederick Soddy at McGill University, Rutherford showed that
elements such as uranium and thorium became different
elements (i.e., transmuted) through the process of radioactive
decay.
A Closer Look
Atomic Energy
Agenda
•OBJ 4: Calculate ages of objects using halflife.
1. R. decay and Half-life
•Warm-up: To determine the age of an antler
2. Watch your “headsium”
which has one-fourth of its original carbon-14
unchanged, we must : multiply the number of
half-lives that have passed by the length of the
half life for that element (in this case 5,730
years). THUS: 2 x 5,730 yrs = 11,460 yrs.
YOUR TURN: what is the age of a spear
containing one-eighth its original amount of
carbon-14?
•Homework: Read and take notes on pages
88-94.
Half-life
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The amount of time it takes for one-half of the
nuclei of a radioactive isotope to decay.
Radiu
m
%
Remaining
0
1620 3240 6480
12960 25920 51840
100% 50% 25% 12.5% 6.25% 3.125 1.56%
%
Iodine
%
Remaining
100% 50% 25% 12.5% 6.25% 3.125 1.56%
%
Uraniu
m
%
100% 50% 25% 12.5% 6.25% 3.125 1.56%
Remaining
%
Radioactive Decay & the
Half-life
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Using the information on page 86, answer the following
questions:
1. A 20 g nitrogen-13 sample is prepared for an experiment. If a
scientist begins the experiment 20 minutes later, how many grams of
nitrogen-13 remain?
2. At the end of the experiment, if only 2.5 g of nitrogen-13 remain, how
much time has passed from the time the sample was prepared?
3. Sodium-24 has a half-life of 15 hours. There are 5 grams of Sodium24 at time 0. How long will it take to have 1.25 grams remaining?
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Handout
Please copy the following
Trials
Number of “headsium” nuclei remaining
0
100
1
2
3
4
5
6
7
8
Conclusion
Take several minutes and complete the
Section Review on page 87
Atomic Energy
•OBJ 5:
Understand the difference between
nuclear fusion & fission.
•OBJ 6: Identify advantages and
disadvantages of energy from the nucleus.
•Warm-up: Complete the Section Review on
page 93.
•Homework: Complete the Chapter Review on
pg 98 #1-10 (this will be graded!) *Possible
POP QUIZ next week!
Agenda
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Finish QuickLab questions/ graph
Finish worksheet
Nuclear Fusion/Fission
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Nuclear Fission: when a large nucleus splits into
two smaller nuclei with the release of energy
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Some nuclei can undergo fission naturally
Hit with neutrons
Chain reaction
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Nuclear Fusion: 2 or more nuclei with small
masses join together to form a larger, more
massive nucleus
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The repulsion of + + has to be overcome…only
way is with high temps (100,000,000 degrees)
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Occurs naturally in the sun’s core
Can we use nuclear fusion?
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1. When you wrap the Mobium in a few sheets of
paper, your instruments cannot detect its
radiation. What kind of radiation is Mobium
probably emitting?
2. 24 hours after isolating Mobium, you determine
that all but 6.25% of it has turned into iron. What is
Mobium’s half-life?
3. Rounding to the nearest whole number
percentage point, after how many hours will
~100% of the Mobium have turned into iron?
Atomic Energy
•OBJ 5:
Understand the difference between
nuclear fusion & fission.
•OBJ 6: Identify advantages and
disadvantages of energy from the nucleus.
•Warm-up: Turn in Chapter Review.
•Homework: Possible POP QUIZ next week!
Agenda
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Check worksheet
Nuclear Fusion/Fission
Domino Chain Reaction Lab
The Effects of Radiation
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Can knock electrons out of atoms
Break chemical bonds between atoms
Can cause damage to living and non-living matter
Radiation sickness
Atomic Energy in Real Life