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CHAPTER 22 Nuclear Chemistry. I. The Nucleus (p. 701 - 704). I. II. III. IV. B. Nuclear Binding Energy. Energy released when a nucleus is formed from nucleons. High binding energy = stable nucleus. E = mc 2. E:energy (J) m:mass defect (kg) c:speed of light (3.00×10 8 m/s). - PowerPoint PPT Presentation
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CHAPTER 22 Nuclear
Chemistry
I. The Nucleus(p. 701 - 704)
I
IV
III
II
B. Nuclear Binding Energy
Energy released when a nucleus is formed from nucleons.
High binding energy = stable nucleus.
E = mc2E: energy (J)m: mass defect (kg)c: speed of light
(3.00×108 m/s)
CHAPTER 22 Nuclear
Chemistry
II. Radioactive Decay
(p. 705 - 712)
I
IV
III
II
He42
A. Types of RadiationAlpha particle ()
helium nucleus
paper2+
Beta particle (-) electron e0
-11- lead
Positron (+) positron e0
11+
Gamma () high-energy photon 0
concrete
B. Nuclear DecayAlpha Emission
He Th U 42
23490
23892
parentnuclide
daughternuclide
alphaparticle
Numbers must balance!!
B. Nuclear DecayBeta Emission
e Xe I 0-1
13154
13153
electronPositron Emission
e Ar K 01
3818
3819
positron
B. Nuclear DecayElectron Capture
Pd e Ag 10646
0-1
10647
electronGamma Emission
Usually follows other types of decay.Transmutation
One element becomes another.
B. Nuclear DecayWhy 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 TRANSPARENCY
C. Half-lifeHalf-life (t½)
Time required for half the atoms of a radioactive nuclide to decay.
Shorter half-life = less stable.
C. Half-life
nif mm )( 2
1
mf: final massmi: initial massn: # of half-lives
C. Half-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 smi = 25 gmf = ?total time = 60.0 sn = 60.0s ÷ 5.0s =12
WORK:mf = mi (½)n
mf = (25 g)(0.5)12
mf = 0.0061 g
CHAPTER 22 Nuclear
Chemistry
III. Fission & Fusion
(p. 717 - 719)
I
IV
III
II
A. F issionsplitting a nucleus into two or more smaller
nuclei1 g of 235U =
3 tons of coal
U23592
A. F issionchain reaction - self-propagating reactioncritical mass -
mass required to sustain a chain reaction
B. Fusioncombining 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
C. Fission vs. Fusion
235U is limiteddanger of
meltdown toxic waste thermal pollution
fuel is abundantno danger of
meltdownno toxic wastenot yet sustainable
FISSION
FUSION
CHAPTER 22 Nuclear
Chemistry
IV. Applications(p. 713 - 716)
I
IV
III
II
A. Nuclear PowerFission Reactors Cooling Tower
A. Nuclear PowerFission Reactors
A. Nuclear PowerFusion Reactors (not yet sustainable)
A. Nuclear PowerFusion Reactors (not yet sustainable)
Tokamak Fusion Test Reactor
Princeton University
National Spherical Torus Experiment
B. Synthetic 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
C. Radioactive Datinghalf-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
D. Nuclear MedicineRadioisotope 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.
E. Nuclear WeaponsAtomic 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
F. OthersFood Irradiation
radiation is used to kill bacteriaRadioactive Tracers
explore chemical pathways trace water flow study plant growth, photosynthesis
Consumer Products ionizing smoke detectors - 241Am