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Nuclear Chemistry

Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

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Page 1: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Chemistry

Page 2: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

23.1

Page 3: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Reactions vs. Nuclear Reactions vs. Normal Chemical Normal Chemical

ChangesChanges• Nuclear reactions involve the nucleusNuclear reactions involve the nucleus• The nucleus opens, and protons and The nucleus opens, and protons and

neutrons are rearrangedneutrons are rearranged• The opening of the nucleus releases a The opening of the nucleus releases a

tremendous amount of energy that holds tremendous amount of energy that holds the nucleus together – called the nucleus together – called binding binding energyenergy

• ““Normal” Chemical Reactions involve Normal” Chemical Reactions involve electronselectrons, not protons and neutrons, not protons and neutrons

Page 4: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

I. Nuclear Chemistry

A. Wilhem Rontgen - discovered x-rays in 1895

B. Antoine Henri Becquerl - discovered radioactivity

1. photographic plates and rocks

C. Marie and Pierre Curie - discovered other radioactive elements

1. Marie first person to win the Nobel peace prizetwice

Page 5: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

2. husband run over by wagon when he was crossing the street

3. Marie and her children died of radiation poisoning

Page 6: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

RadioactivityRadioactivity

• One of the pieces of evidence for the One of the pieces of evidence for the fact that atoms are made of smaller fact that atoms are made of smaller particles came from the work ofparticles came from the work of

Marie CurieMarie Curie (1876-1934).(1876-1934). • She discoveredShe discovered radioactivityradioactivity, ,

the spontaneous disintegration of the spontaneous disintegration of some elements into smaller pieces.some elements into smaller pieces.

Page 7: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

II. Radioactivity

A. Spontaneous break down of an unstable nucleus with the release of particles and rays

B. Mass defect and nuclear stability

1. the sum of the particles(protons, neutrons and electrons) that make up an atom but does not add up to the mass of an atom

2. the difference between the sum of the masses and the atomic mass is know as the mass defect

Page 8: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Mass DefectMass Defect

• Some of the mass can be converted into Some of the mass can be converted into energyenergy

• Shown by a very famous equation!Shown by a very famous equation!

E=mcE=mc22

EnergyEnergy

MassMass

Speed of lightSpeed of light

Page 9: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

C. Nuclear binding energy

1. The energy released when a nucleus is formedfrom nucleons (protons and neutrons)

Page 10: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

III Properties of Radioactive elements

1. They affect photographic film

2. They produce electric charges in the surrounding air

3. They produce fluorescence with certain compounds

a. fluorescence - makes thing glow

Page 11: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

4. Their radiation’s have special physiological effects

a. causes mutations in cells - changes in the

DNA of cells causing rapid growth and a

change in their function

5. They undergo radioactive decay

a. Radioactive decay - they emit particles from the nucleus making simpler atoms

i. half-life - the time it takes 1/2 a given

amount to decay

ii. Half-lives can be from a few seconds

to millions of years

Page 12: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Half-LifeHalf-Life

• HALF-LIFEHALF-LIFE is the time that it takes for is the time that it takes for 1/2 a sample to decompose.1/2 a sample to decompose.

• The rate of a nuclear transformation The rate of a nuclear transformation depends only on the “reactant” depends only on the “reactant” concentration.concentration.

Page 13: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Kinetics of Radioactive Kinetics of Radioactive DecayDecay

For each duration (half-life), one half of the substance

decomposes.

For example: Ra-234 has a half-life of 3.6 days

If you start with 50 grams of Ra-234

After 3.6 days > 25 gramsAfter 3.6 days > 25 grams

After 7.2 days > 12.5 gramsAfter 7.2 days > 12.5 grams

After 10.8 days > 6.25 gramsAfter 10.8 days > 6.25 grams

Page 14: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Half-LifeHalf-Life

Decay of 20.0 mg of Decay of 20.0 mg of 1515O. What remains after 3 half-lives? O. What remains after 3 half-lives? After 5 half-lives?After 5 half-lives?

Page 15: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

e.g. The half-life of Plutonium -239 is 24110 years. Of an original mass of 100. g, how much remains after 96440 years

first find the number of half-life's

# Half-lifes = 96440 years 24110 Years

= 4

now divide the gram sample in 1/2 four times

100 ===> 6.25===>12.5===> 25===> 50

1 2 3 4

Page 16: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

The half-life of thorium -227 is 18.72 days. How many days are required for 3/4 of a given amount to decay

1 ===> 1/2 ===> 1/4

This tells you that you have 1/4 of the original amount left - therefore - 3/4 of a given amount has decayed

you must multiply 18.72 days by 2 == 37.44 days

18.72 days 18.72 days

Page 17: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

e.g Exactly 1/16 of a given amount of protactinium-234 remains after 26.76 hours. What is the half-life of

protactinium - 234

First find the number of half-life's

1 ==> 1/2 ===> 1/4 ===> 1/8 ===> 1/16

You must pass threw 4 half life’s

26.76 hours4 half-life’s

= 6.69 hours/half-life

Page 18: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 78 hours?

Page 19: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Stability

• Certain numbers of neutrons and protons are extra stable

• n or p = 2, 8, 20, 50, 82 and 126

• Like extra stable numbers of electrons in noble gases (e- = 2, 10, 18, 36, 54 and 86)

• Nuclei with even numbers of both protons and neutrons are more stable than those with odd numbers of neutron and protons

• All isotopes of the elements with atomic numbers higher than 83 are radioactive

• All isotopes of Tc and Pm are radioactive

23.2

Page 20: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Band of Stability and Band of Stability and Radioactive DecayRadioactive Decay

When the number of protons in a stable nuclei is plotted against the number of neutrons

Page 21: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Stability Stability of of NucleiNuclei

• Out of > 300 stable isotopes:

EvenEven OddOdd

OddOdd

EvenEven

ZZNN

157157 5252

5050 55

31311515PP

191999FF

2211H, H, 66

33Li, Li, 101055B, B, 1414

77N, N, 1801807373TaTa

Page 22: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Radioactive decay

1. types of particles

a. alpha particles, contain two protons and

two neutrons - can be stopped by a piece of

paper - have low penetrating power - may

cause burns to the flesh

b. beta particles,, high speed electrons, travel at close to the speed of light, c, which is

equal to 3 x 108 m/sec or 186,000 miles a sec

c. gamma rays,, are high energy electromagnetic waves. Most penetrating

Page 23: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Types of RadiationTypes of Radiation

e01

He42

• Alpha – a positively charged Alpha – a positively charged (+2) helium isotope(+2) helium isotope - - we usually we usually ignore the charge because it involves electrons, ignore the charge because it involves electrons, not protons and neutronsnot protons and neutrons

•Beta – an electronBeta – an electron

•Gamma – pure energy; Gamma – pure energy; called a ray rather than a called a ray rather than a particleparticle

00

Page 24: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Other Nuclear ParticlesOther Nuclear Particles

e01

n10• NeutronNeutron

• Positron – a positive Positron – a positive electronelectron

•Proton – usually referred to Proton – usually referred to as hydrogen-1as hydrogen-1

•Any other elemental isotopeAny other elemental isotope

H11

Page 25: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Penetrating AbilityPenetrating Ability

Page 26: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

XAZ

Mass Number

Atomic NumberElement Symbol

Atomic number (Z) = number of protons in nucleus

Mass number (A) = number of protons + number of neutrons

= atomic number (Z) + number of neutrons

A

Z

1p11H1or

proton1n0

neutron0e-1

0-1or

electron0e+1

0+1or

positron4He2

42or

particle

1

1

1

0

0

-1

0

+1

4

2

23.1

Page 27: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

3. radioactive decay sequence

238U92 ----> + 234Th90

parent daughter

when you have an alpha ejection - you lose 2 protons and 2 neutron

The 92 of uranium is the number of protons and will go to 90 with an alpha ejection - the number of protons in you nucleus determines the element.

Page 28: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The
Page 29: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

therefore - U turns into Th

The 238 of U is the total number of particles in

the nucleus = number of protons and neutrons -

with an alpha ejection - you lose 2 protons and 2

neutrons your mass goes down by 4 or become 234

226Ra88 ----> + 222Rn86

Page 30: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

When you have a beta ejection - you have a neutron change to a protons thus causing your number of protons to go up by one. The total number of particles in the nucleus does not change

234Pa91 ----> 234U92

+ beta particle

234Th90 ---->234Pa91

+

Page 31: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The
Page 32: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

On page 724 do problems 33,34,35,40,41,42,43

Page 33: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

212Po decays by alpha emission. Write the balanced nuclear equation for the decay of 212Po.

4He242oralpha particle -

212Po 4He + AX84 2 Z

212 = 4 + A A = 208

84 = 2 + Z Z = 82

212Po 4He + 208Pb84 2 82

23.1

Page 34: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Stability and Radioactive Decay

Beta decay

14C 14N + 0 + 6 7 -1

40K 40Ca + 0 + 19 20 -1

1n 1p + 0 + 0 1 -1

Decrease # of neutrons by 1

Increase # of protons by 1

Positron decay

11C 11B + 0 + 6 5 +1

38K 38Ar + 0 + 19 18 +1

1p 1n + 0 + 1 0 +1

Increase # of neutrons by 1

Decrease # of protons by 1

and have A = 0 and Z = 023.2

Page 35: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Electron capture decay

Increase # of neutrons by 1

Decrease # of protons by 1

Nuclear Stability and Radioactive Decay

37Ar + 0e 37Cl + 18 17-1

55Fe + 0e 55Mn + 26 25-1

1p + 0e 1n + 1 0-1

Alpha decay

Decrease # of neutrons by 2

Decrease # of protons by 2212Po 4He + 208Pb84 2 82

Spontaneous fission

252Cf 2125In + 21n98 49 023.2

Page 36: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

What radioactive isotope is produced in the following bombardment of boron?

10B + 4He ? + 1n

5 2 0

Page 37: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

What radioactive isotope is produced in the following bombardment of boron?

10B + 4He 13N + 1n

5 2 7 0

Page 38: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Write Nuclear Equations!

Write the nuclear equation for the beta emitter Co-60.

6060CoCo 00ee ++ 6060NiNi2727 -1 -1 2828

Page 39: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Positron emission -conversion of a proton to a neutron bythe emission of a positron

1. Positron - particle that has the same mass as an

electron, but has a positive charge

Gamma radiation - does not change the identity of the element but makes the atom more stable

Transmutation - changing the identity of an element through the release of radioactive particles

Isotopes - atoms of the same element that have different number of neutrons

Page 40: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Geiger-Müller Counter

23.7

Page 41: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Geiger Counter

• Used to detect radioactive substances

Page 42: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Artificial Nuclear Artificial Nuclear ReactionsReactions

New elements or new isotopes of known elements New elements or new isotopes of known elements are produced by bombarding an atom with a are produced by bombarding an atom with a subatomic particle such as a proton or neutron -- subatomic particle such as a proton or neutron -- or even a much heavier particle such as or even a much heavier particle such as 44He and He and 1111B.B.

Reactions using neutrons are called Reactions using neutrons are called

reactions reactions because a because a ray is usually ray is usually emitted.emitted.

Radioisotopes used in medicine are often made by Radioisotopes used in medicine are often made by reactions. reactions.

Page 43: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Artificial Nuclear Artificial Nuclear ReactionsReactions

Example of a Example of a reaction reaction is production is production

of radioactive of radioactive 3131P for use in studies of P P for use in studies of P

uptake in the body.uptake in the body.

31311515P + P + 11

00n ---> n ---> 32321515P + P +

Page 44: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Transuranium ElementsTransuranium Elements

Elements beyond 92 Elements beyond 92 (transuranium)(transuranium) made made

starting with an starting with an reaction reaction

2382389292U + U + 11

00n ---> n ---> 2392399292U + U +

2392399292U U ---> ---> 239239

9393Np + Np + 00-1-1

2392399393Np Np ---> ---> 239239

9494Pu + Pu + 00-1-1

Page 45: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

23.8

Biological Effects of RadiationRadiation absorbed dose (rad)

1 rad = 1 x 10-5 J/g of material

Roentgen equivalent for man (rem)

1 rem = 1 rad x Q Quality Factor-ray = 1

= 1 = 20

Page 46: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Effects of RadiationEffects of Radiation

Page 47: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear FissionNuclear FissionFission is the splitting of atomsFission is the splitting of atoms

These are usually very large, so that they are not as stableThese are usually very large, so that they are not as stable

Fission chain has three general steps:Fission chain has three general steps:

1.1. Initiation.Initiation. Reaction of a single atom starts the Reaction of a single atom starts the

chain (e.g., chain (e.g., 235235U + neutron)U + neutron)

2.2. PropagationPropagation. . 236236U fission releases neutrons that U fission releases neutrons that

initiate other fissionsinitiate other fissions

3. 3. TerminationTermination. .

Page 48: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear FissionNuclear Fission

Page 49: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Fission

23.5

235U + 1n 90Sr + 143Xe + 31n + Energy92 54380 0

Energy = 3.3 x 10-11J per 235U

= 2.0 x 1013 J per mole 235U

Combustion of 1 ton of coal = 5 x 107 J

= 235 grams = 0.5 lbs

Page 50: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Representation of a fission process.

Page 51: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Fission

23.5

Nuclear chain reaction is a self-sustaining sequence of nuclear fission reactions.The minimum mass of fissionable material required to generate a self-sustaining nuclear chain reaction is the critical mass.

Non-critical

Critical

Page 52: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Fission & Nuclear Fission & POWERPOWER

• Currently about 103 Currently about 103

nuclear power plants in nuclear power plants in

the U.S. and about 435 the U.S. and about 435

worldwide.worldwide.

• 17% of the world’s 17% of the world’s

energy comes from energy comes from

nuclear.nuclear.

Page 53: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Diagram of a nuclear power plant

Page 54: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Annual Waste Production

23.5

35,000 tons SO2

4.5 x 106 tons CO2

1,000 MW coal-firedpower plant

3.5 x 106

ft3 ash

1,000 MW nuclearpower plant

70 ft3 vitrified waste

Nuclear Fission

Page 55: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Fusion

Fusion small nuclei combine

2H + 3H 4He + 1n +

1 1 2 0

Occurs in the sun and other stars

Energy

Page 56: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear Fusion

Fusion

• Excessive heat can not be contained

• Attempts at “cold” fusion have FAILED.

• “Hot” fusion is difficult to contain

Page 57: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

23.7

Radioisotopes in Medicine• 1 out of every 3 hospital patients will undergo a nuclear

medicine procedure

• 24Na, t½ = 14.8 hr, emitter, blood-flow tracer

• 131I, t½ = 14.8 hr, emitter, thyroid gland activity

• 123I, t½ = 13.3 hr, ray emitter, brain imaging

• 18F, t½ = 1.8 hr, emitter, positron emission tomography

• 99mTc, t½ = 6 hr, ray emitter, imaging agent

Brain images with 123I-labeled compound

Page 58: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

protection from radiation

A. Shielding

sunscreen, lead apron

B. distance

- inverse square law

Page 59: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The
Page 60: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The
Page 61: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The
Page 62: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nagasaki JapanAugust 9, 1945

Page 63: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Nuclear review

1. A radioactive atom will lose the greatest amount of mass when it emits 1. a neutron' 3.a beta particle , 2. a proton 4.an alpha particle

2 A sample of iodine-131 contains 10. grams. Approximately how much iodine-131 will remain after 24 days

(half life -8 days)? 1. 1.25g 3. 5.0 g

2. 2.5 g 4. 10. g

3. What is the moderator in a nuclear reactor? 1. carbon dioxide 3. cadmium 2. boron 4. graphite

You have a review test

Page 64: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

4. In the reaction 90Th234 -> 91Pa234 + X, X represents

1.a neutron 3. an alpha particle 2.a positron 4. a beta particle

5. One of the biggest advantages of a fusion reactor is it 1. produces no radioactive wastes 2. is small in size 3. will never explode 4. has no reaction control problem

6. Which particle has the least mass? 1. alpha particle 2. proton 3. neutron 4. electron

Page 65: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

7. A neutron has approximately the same mass as 1. an alpha particle 3. an electron 2. a beta particle 4. a proton

8. When 88Ra226 emits an alpha particle, the resulting atom is

1. 86 Rn 2 2 2

2. 86 Rn 2 2 4

3. 88 Ra 2 2 2

4. 88 Ra 2 2 4

9. To make nuclear fission nuclear reactor more efficient, which device is used to slow the speed of neutrons?

1. internal shield 2. external shield 3.control rod 4.moderator

10. If radioactive substance has a half-life of 9 days, what fraction of its original mass would remain after 27 days? 1. 1/8 2. 1/4 3. 1/2 4. 3/4

Page 66: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

11. Which reaction illustrates fusion? 1. 1 H

2 + 1 H2 ===> 2He4

2. on1 + 13A127 ==> 11Na24 + 2He4

3. 13A127 + 2He4 ===> 15P30 + 2 He4 + 0 n

1

4. 7 N1 4 + 2 He4 ===> 1 H

1 + 8O17

12.Control rods in nuclear reactors are commonly made of boron and cadmium because these two elements have the ability to 1) absorb neutrons 2) emit neutrons 3) decrease the speed of neutrons 4) increase the speed of neutrons

13. If iodine-131 undergoes beta decay, which symbol represents the resulting nucleus?

1. 52Te132 2. 54Xe131 3. 53I130 4. 51 Sb1 27

Page 67: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

14. Which element is formed when 82Pb214 emits a beta particle?

1. 84 Po 21 8 2. 80 Hg 2 0 0 3. 83Bi213 4. 83Bi214

15.Radioactive changes differ from ordinary chemical changes In that radioactive changes 1.are explosive 3.involve changes in the nucleus 2.absorb energy 4.release energy

16. In the reaction

4Be9 + X ----> 6 C12 + 0 n1 the X represents

1.an alpha particle 3.an electron 2.a beta particle 4.a proton

Page 68: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

18. Which nuclear equation represents beta decay? 1. 13A127 + 2He4 --> 15P

30 + on1

2 . 92 U2 3 8 -- -> 90 Th2 3 4 + 2 He4

3. 6 C1 4 - -> 7 N

1 4 + - 1 e0

4. 18Ar37 + -1 eo --> 17Cl37

19. An atom of Ra226 decays to Rn222 by emitting 1.a proton 3. an alpha particle 2.an electron 4. a beta particle

20. Heavy water may be used in a nuclear reactor as a 1.moderator 3. shielding 2.fuel 4. control rod

21.When an atom emits a beta particle, the total number of nucleons 1. decreases 2. increases 3. remains the same

Page 69: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

22. The radioactive particle or ray with the greatest penetrating power is the

1.alpha particle 3.gamma ray 2.beta particle 4.proton

23. The major portion of an atom's mass consists of 1) electrons and protons 3) neutrons and positrons 2) electrons and neutrons 4) neutrons and protons

24. During a chain reaction the number of nuclei reacting per second 1. increases 2. decreases 3. remains the same

Page 70: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

25. A radioactive source emits radiation which is deflected as shown in the diagram. .

This radiation could be

1. _1eo

2. 2 He4

3. 1 H1

4. 0 n1

Page 71: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

26.When 90Th234 emits a beta particle ( -1 e0), the element

formed is 1. Ra 2. Th 3. Pa 4. U

27. A 40.0 milligram sample of phosphorus -33 decays to 10.0 milligrams in 50.0 days. What is the half-life of

phosphorus-33? 1.12.5 days 3.37.5 days 2.25.0 days 4.75.0 days

28. During a fission reaction, which type of particle is captured by a nucleus? 1.deuterium 3.neutron 2.electron 4.proton

29.When two light nuclei combine into a heavier nucleus, the process is called

1.fission 3.beta decay 2.fusion 4.nuclear disintegration

Page 72: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

30, An electron has a charge identical to that of 1. a neutron 3. an alpha particle 2.a proton 4. a beta particle

31. In the reaction 92U238 --> 90Th234 + X, X represents

1.a beta particle 3. a positron 2.a neutron 4. an alpha particle

Page 73: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

23.6

Nuclear Fusion

2H + 2H 3H + 1H1 1 1 1

Fusion Reaction Energy Released

2H + 3H 4He + 1n1 1 2 0

6Li + 2H 2 4He3 1 2

6.3 x 10-13 J

2.8 x 10-12 J

3.6 x 10-12 J

Tokamak magnetic plasma

confinement

Page 74: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Balancing Nuclear Equations

1. Conserve mass number (A).

The sum of protons plus neutrons in the products must equal the sum of protons plus neutrons in the reactants.

1n0U23592 + Cs138

55 Rb9637

1n0+ + 2

235 + 1 = 138 + 96 + 2x1

2. Conserve atomic number (Z) or nuclear charge.

The sum of nuclear charges in the products must equal the sum of nuclear charges in the reactants.

1n0U23592 + Cs138

55 Rb9637

1n0+ + 2

92 + 0 = 55 + 37 + 2x023.1

Page 75: Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Radiocarbon Dating

14N + 1n 14C + 1H7 160

14C 14N + 0 + 6 7 -1 t½ = 5730 years

Uranium-238 Dating

238U 206Pb + 8 4 + 6 092 -182 2 t½ = 4.51 x 109 years

23.3