CHAPTERCHAPTER 2222
Nuclear NuclearChemistryChemistry
CHAPTERCHAPTER 2222
Nuclear NuclearChemistryChemistry
I. The NucleusI. The Nucleus(p. 701 - 704)
I. The NucleusI. The Nucleus(p. 701 - 704)
I
IV
III
II
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Nuclear Binding Nuclear Binding EnergyEnergy
Nuclear Binding Nuclear Binding EnergyEnergy
Unstable nuclides are radioactive and undergo radioactive decay.
U-238
10x108
9x108
8x108
7x108
6x108
5x108
4x108
3x108
2x108
1x108
Fe-56
B-10
Li-6
H-2
He-4
00 20 40 60 80 100 120 140 160 180 200 220 240
Mass number
Bin
ding
ene
rgy
per
nucl
eon
(kJ/
mol
)
CHAPTERCHAPTER 2222
Nuclear Nuclear Chemistry Chemistry
CHAPTERCHAPTER 2222
Nuclear Nuclear Chemistry Chemistry
II. Radioactive II. Radioactive DecayDecay
(p. 705 - 712)
II. Radioactive II. Radioactive DecayDecay
(p. 705 - 712)
I
IV
III
II
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He42
Types of RadiationTypes of RadiationTypes of RadiationTypes of Radiation
Alpha particle () helium nucleus paper2+
Beta particle (-) electron e0
-11-
leadPositron (+)
positron e01
1+
Gamma () high-energy photon 0
concrete
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Nuclear DecayNuclear DecayNuclear DecayNuclear Decay
Alpha Emission
He Th U 42
23490
23892
parentnuclide
daughternuclide
alphaparticle
Numbers must balance!!
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Nuclear DecayNuclear DecayNuclear DecayNuclear Decay
Beta Emission
e Xe I 0-1
13154
13153
electronPositron Emission
e Ar K 01
3818
3819
positronCourtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Nuclear DecayNuclear DecayNuclear DecayNuclear Decay
Electron Capture
Pd e Ag 10646
0-1
10647
electron Gamma Emission
Usually follows other types of decay.
Transmutation One element becomes another.
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120
100
80
60
40
20
0
Neu
tro
ns
(A-Z
)
0 20 40 60 80 100 120Protons (Z)
Nuclear DecayNuclear DecayNuclear DecayNuclear Decay
Why nuclides decay… need stable ratio of neutrons to protons
He Th U 42
23490
23892
e Xe I 0-1
13154
13153
e Ar K 01
3818
3819
Pd e Ag 10646
0-1
10647 DECAY SERIES TRANSPARENCYCourtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
P = N
e-captureor
e+ emission
stable nuclei
120
100
80
60
40
20
0N
eutr
on
s (A
-Z)
P = N
0 20 40 60 80 100 120Protons (Z)
stable nuclei
e-captureor
e+ emission
120
100
80
60
40
20
0
Neu
tro
ns
(A-Z
)
P = N
0 20 40 60 80 100 120Protons (Z)
stable nuclei
Why nuclides decay… need stable ratio of neutrons to protons
Nuclear DecayNuclear DecayNuclear DecayNuclear Decay
Half-lifeHalf-lifeHalf-lifeHalf-life
Half-life (t½) Time required for half the atoms of a
radioactive nuclide to decay. Shorter half-life = less stable.
1/1
1/2
1/4
1/8
1/160R
ati
o o
f R
em
ain
ing
Pota
ssiu
m-4
0 A
tom
sto
Ori
gin
al Pota
ssiu
m-4
0 A
tom
s
0 1 half-life1.3
1 half-lives2.6
3 half-lives3.9
1 half-lives5.2
Time (billions of years)Time (billions of years)
Newly formed rockPotassium
Argon
Calcium
Half-lifeHalf-lifeHalf-lifeHalf-life
nif mm )( 2
1
mf: final massmi: initial massn: # of half-lives
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Half-lifeHalf-lifeHalf-lifeHalf-life Fluorine-21 has a half-life of 5.0 seconds. If you
start with 25 g of fluorine-21, how many grams would remain after 60.0 s?
GIVEN: t½ = 5.0 s
mi = 25 g
mf = ?
total time = 60.0 s
n = 60.0s ÷ 5.0s =12
WORK: mf = mi (½)n
mf = (25 g)(0.5)12
mf = 0.0061 g
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CHAPTERCHAPTER 2222
Nuclear Nuclear Chemistry Chemistry
CHAPTERCHAPTER 2222
Nuclear Nuclear Chemistry Chemistry
III. Fission & III. Fission & FusionFusion
(p. 717 - 719)
III. Fission & III. Fission & FusionFusion
(p. 717 - 719)
I
IV
III
II
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FF issionissionFF issionission
splitting a nucleus into two or more smaller nuclei
1 g of 235U = 3 tons of coal
U23592
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FF issionissionFF issionissionchain reaction - self-propagating reactioncritical mass -
mass required to sustain a chain reaction
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FusionFusionFusionFusioncombining of two nuclei to form one nucleus of larger mass thermonuclear reaction – requires temp of 40,000,000 K to sustain1 g of fusion fuel =
20 tons of coaloccurs naturally in
stars
HH 31
21
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Fission vs. FusionFission vs. FusionFission vs. FusionFission vs. Fusion
235U is limited danger of meltdown toxic waste thermal pollution
fuel is abundant no danger of meltdown no toxic waste not yet sustainable
FISSION
FUSION
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CHAPTERCHAPTER 2222
Nuclear NuclearChemistryChemistry
CHAPTERCHAPTER 2222
Nuclear NuclearChemistryChemistry
IV. ApplicationsIV. Applications(p. 713 - 716)
IV. ApplicationsIV. Applications(p. 713 - 716)
I
IV
III
II
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Nuclear PowerNuclear PowerNuclear PowerNuclear Power
Fission Reactors Cooling Tower
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Nuclear PowerNuclear PowerNuclear PowerNuclear Power
Fission Reactors
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Nuclear PowerNuclear PowerNuclear PowerNuclear Power
Fusion Reactors (not yet sustainable)
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ITER(International ThermonuclearExperimental Reactor)
TOROIDALFIELD COILS(produces the magnetic fieldwhich confines the plasma)
BLANKET(provides neutron shieldingand converts fusion energyinto hot, high pressure fluid)
FUSIONPLASMACHAMBER(where the fusionreactions occur)
Height 100 feetDiameter 100 feetFusion power 1100 Megawatts
Nuclear PowerNuclear PowerNuclear PowerNuclear Power
Fusion Reactors (not yet sustainable)
Tokamak Fusion Test Reactor
Princeton University
National Spherical Torus Experiment
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Synthetic ElementsSynthetic ElementsSynthetic ElementsSynthetic ElementsTransuranium Elements
elements with atomic #s above 92 synthetically produced in nuclear reactors and accelerators most decay very rapidly
Pu He U 24294
42
23892
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Natural and artificial radioactivity
Natural radioactivityIsotopes that have been here since the earth formed.
Example - Uranium
Produced by cosmic rays from the sun.Example – carbon-14
Man-made RadioisotopesMade in nuclear reactors when we split atoms (fission).
Produced using cyclotrons, linear accelerators,…
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Positiveparticlesource
Alternatingvoltage
Particlebeam
VacuumTarget
Radioactive DatingRadioactive DatingRadioactive DatingRadioactive Dating
half-life measurements of radioactive elements are used to determine the age of an object
decay rate indicates amount of radioactive material
EX: 14C - up to 40,000 years238U and 40K - over 300,000
years
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Nuclear MedicineNuclear MedicineNuclear MedicineNuclear Medicine
Radioisotope Tracers absorbed by specific organs and
used to diagnose diseases
Radiation Treatment larger doses are used
to kill cancerous cells in targeted organs
internal or external radiation source Radiation treatment
using-rays from cobalt-60.
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Nuclear WeaponsNuclear WeaponsNuclear WeaponsNuclear Weapons
Atomic Bomb chemical explosion is used to form a
critical mass of 235U or 239Pu fission develops into an uncontrolled
chain reaction Hydrogen Bomb
chemical explosion fission fusion fusion increases the fission rate more powerful than the atomic bomb
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OthersOthersOthersOthers
Food Irradiation radiation is used to kill bacteria
Radioactive Tracers explore chemical pathways trace water flow study plant growth, photosynthesis
Consumer Products ionizing smoke detectors - 241Am
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Simplified diagram of fission bomb
Subcriticalmasses
Chemical Explosive
Criticalmass