50
Chapter 22 Nuclear Reactions

Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Embed Size (px)

DESCRIPTION

Nuclear Rxns Nuclide (Nucleus of an atom) Contains nucleons(protons and neutrons)

Citation preview

Page 1: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Chapter 22Nuclear Reactions

Page 2: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Rxns Nuclear reaction-a reaction that

involves a change in an atom’s nucleus.

Therefore, an atom of one element changes into an atom of another element.

Page 3: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Rxns Nuclide (Nucleus of an atom)

Contains nucleons(protons and neutrons)

Page 4: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Chemical vs. Nuclear Rxns.

Associated with large energy changes

Associated with small energy changes

May involve p, nInvolve only outer electrons

Atoms are often converted into atoms of another element.

Atoms remain unchanged, just rearranges

Occur when nuclei emit particles and/or rays

Occur when bonds are broken and formed

Nuclear RxnsChemical Rxns

Page 5: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Radiation Radiation-The rays and particles

that are emitted by radioactive materials.

Page 6: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Alpha Radiation Alpha radiation-radiation deflected

towards the negatively charged plate and gives off alpha particles

Alpha particles, He or α : 2p, 2n so +2 charge, largest mass (4 amu)

Page 7: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Beta Radiation Beta radiation-radiation deflected

towards the positively charged plate and gives off beta particles (electrons).

Beta particles, β or e: 1e so -1 charge, mass is between alpha and gamma particles

Page 8: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Gamma Radiation Gamma radiation-radiation deflected

towards no plate and gives off gamma rays

Gamma rays, γ : no mass and no charge, usually occupied by α and β

decay.

Page 9: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Rxns (1) Ra → Rn + He

α decay

(2) C → N + e β decay

(3) U → Th + He + 2γ γ decay

Page 10: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Types of Radiation (Memorize) Consists Charge Mass Stopped w/ symbol

Alpha

Beta

Gamma

Page 11: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Types of Radiation Positron emission-radioactive decay

that involves the emission of a positron from a nucleus (antimatter)

Positron-particle with the same mass as the electron but opposite charge

• Symbol:

Page 12: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Types of Radiation Electron Capture- nucleus of an

atom draws in a surrounding electron and an X-ray photon is emitted Symbol:

Page 13: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Reactions Nuclear Rxn- a rxn that changes the

nucleus

Transmutation-a change in the identity of the nucleus, change in # of protons in nucleus.

Page 14: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear StabilityMass defect – diff. between mass of an

atom and sum of masses for p, n, e.

Why loss of mass?Caused by conversion of mass to

energy upon formation of nucleus

Page 15: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Binding energy – energy released upon formation of nucleus

Page 16: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Stability The smaller stable nuclides have a

neutron-proton of 1:1 to the larger nuclides of 1.5:1.

If the nuclei ratio falls above/below the band of stability, the nuclides will undergo decay until they are within the band of stability.

Page 17: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Radioactive decay Radioactive decay-spontaneous

disintegration of an unstable nucleus to a smaller nucleus by giving off nuclear radiation.

Radioactive nuclide- unstable nucleus that will undergo radioactive decay

Page 18: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear RxnsIdentify the product that balances the

following nuclear rxns.1. 212Po → 4He + ____

2. 230Th → _____ + 4He

3. 238U + 4He → ____ + 1n

4. 27Al + 1n → 24Na + ____

Page 19: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Radioactive decayAlpha Emission

210Po 206Pb + ____Beta Emission

14C 14N + ____Electron Capture (reverse of beta)

106Ag + _____ 106PdPositron emission

11C → 11B + _____

Page 20: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-life Half-Life- t1/2 - the time required for half the

atoms of a radioactive element to decay into another element.

Fluorine-21 has a half life,t1/2, of 5 seconds 1000 atoms F-21500 atoms F-21 250 atoms F-21 1(whole amt) ½ left ¼ left 100 g F-21 50 g F-21 25 g F-21

Page 21: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-Life ProblemsFormulas:To determine the number of half-lives that past:

#half-lives past = total timet1/2

To determine amount remaining:

Amount remaining = (Initial amt)1 n

2n= # of half lives past

Page 22: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-Life Problems1. If the radioactive sample of I-131

was 18.5g, what amt is left after 32 days? (t1/2 = 8 days)

Page 23: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-Life Problems2.Iron-59 is used in medicine to

diagnosis blood circulation disorders. The half-life of iron-59 is 44.5 days. How much of a 2.000 mg sample will remain after 133.5 days?

Page 24: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-Life Problems3. If gallium-68 has a half-life of 68.3

minutes, how much of a 10.0 mg sample is left after two half-lives?

Page 25: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Half-Life4. After 15 days only 2 grams remain

of a sample that has a half life of 5 days. How many grams were in the original amount?

5. What is the half life of K-42 if a 750 gram sample decays to 93.75 grams in 24 hours?

Page 26: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

6. The half-life of carbon-14 is 5715 years. A sample has only ¼ of its original amount. What is the age of the sample?

Page 27: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Decay Series Decay Series-a series of radioactive

nuclides produced by successive radioactive decay until a stable nuclide is reached

Page 28: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Decay Series QuestionsUse pg. 814 Write the four nuclear equations of

the uranium-238 decay series. What stable nuclide does U-238

finally become? How long is the half life of U-238?

Page 29: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

U-238 U-238 is found in small amounts in soil and rock,

particularly, shale and granite.

Rn is one of the daughter nuclide of U-238(parent nuclide) decay.

Rn is a radioactive gas that can be a health hazard trapped in homes from cracks and holes in foundation. It can cause lung cancer and birth defects.

Ra-226, Po-210, Pb-210 are found in cigarettes and the lungs of smokers.

Page 30: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Induced Transmutation Induced Transmutation- bombardment

of stable nuclei with charged and uncharged particles. This process is used to make radioactive

nuclides not found nature, like our newly discovered elements.

Page 31: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Induced Transmutation1. Write a balanced nuclear equation forthe induced transmutation of aluminum-27 into phosphorus-30 by alpha particlebombardment. A neutron is emittedfrom the aluminum atom.

Page 32: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Induced Transmutation2. Write the balanced nuclear equationfor the induced transmutation ofaluminum-27 into sodium-24 byneutron bombardment. An alphaparticle is released in the rxn.

Page 33: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Induced TransmutationWhat element would be formed in the

following nuclear rxn?3. 242Cm + 4He ______ + 1n

Page 34: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Radiation Radiation Exposure

Rem-a unit used to measure radiation damage to human tissue like x-rays…

(Complete personal radiation wkst)

Page 35: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Radiation Radiation Detection

Geiger Muller counters -measures electrical pulses on gas ionized by radiation

Film badges Scintillation counter

Page 36: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Geiger Counter

Page 37: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Applications of Nuclear Radiation Radiochemical Dating: 14C 0e + 14N

t1/2 = 5715 yrs

Living organisms absorb 14C through food. This C-14 is a constant amt. When the organism dies, there is no new absorption of C-14. The C-14 decays to N-14. By measuring the amount of C-14 the age may be approximated.

Page 38: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Applications of Nuclear Radiation Radioactive Nuclides in Medicine

Radioactive tracers are radioactive atoms incorporated into substances so they can be followed by radiation detectors.

Ex. Tc-99 used to detect bone cancer, I-131 to detect thyroid problems

Page 39: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Applications of Nuclear Radiation Radioactive Nuclides in Agriculture

Radioactive tracers are used to determine effectiveness of fertilizers.

Cobalt-60 is used to irradiate food, to kill bacteria and insects. It is also used to kill cancer cells.

Page 40: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Waste1. Produced from nuclear power

plants, nuclear weapons manufacturing, medical research,…

2. Containment on nuclear waste from nuclear power plants is on-site and off-site disposal.

Page 41: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Waste*3. Each nuclear reactor has large

pools of water where spent uranium fuel rods can be stored.

4. When the pools are filled, they are sealed in concrete and steel dry casks then moved to permanent storage facilities. There are 77 disposal sites in the US.

Page 42: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Fission

Page 43: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Fission Nuclear Fission- splitting a larger

nucleus to smaller intermediate nuclides Nuclear Reactors use controlled

fission reactions to produced energy by this rxn:

Page 44: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Parts of Nuclear Reactor Chain rxn-self propagating rxn

Fuel- U-235

Moderator-slows down high speed neutrons to CONTINUE chain rxn; uses water, Be, or C(graphite)

Control Rods -absorbs neutrons, thereby controlling rate of fission rxn; made of Cd

Page 45: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Parts of Nuclear Reactor Coolant-water to remove heat to

turbines to generate electricity Containment structure(shielding)-

structure built around reactor to hold in radiation from escaping in case of an accident; server feet thick concrete.

Page 46: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element
Page 47: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Recent Nuclear Accidents 1986 Chernobyl power plant in

Soviet Union-Complete meltdown of core

1979 Three Mile Island, USA-partial meltdown

Page 48: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Nuclear Fusion Nuclear Fusion-small nuclei join to

form larger nuclei Ex. sun and stars fusion releases 20X more energy per

gram than fission Uses: hydrogen bomb and in future

fusion power plants

Page 49: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Fusion Reactors Disadvantages of fusion reactors

Huge input of energy needed to start process

A temperature of 200 million K needed to sustain rxn.

Page 50: Chapter 22 Nuclear Reactions. Nuclear Rxns Nuclear reaction-a reaction that involves a change in an atom’s nucleus. Therefore, an atom of one element

Fusion Reactors Advantages of fusion reactors:

Readily available hydrogen from water Nonradioactive products Can stop rxn by dropping temp. Can produce inexhaustible supply of

energy