nuclear radiation and types

8/14/2019 Nuclear Radiation and Types

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TheThe

NucleusNucleus


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Nuclear stability and radioactive decay Kinetics of radioactive decay

Nuclear transformations Detection and uses of radioactivity

Nuclear fission and fusion

Effects of radiation

The NucleusThe Nucleus


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Nuclear chemistry is theNuclear chemistry is the

study of the nucleusstudy of the nucleus

Electron cloud

Nucleus

Electrons are

very small and

have a negativecharge. They

are light and

far apart

The nucleus

contains protons(+)and neutrons (0).

They are very heavy

and close together.


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How do nuclei stickHow do nuclei stick

together?together?

Protons are allpositive and repel

each other. This is the

electronic force.

All nucleons (p, n)

have a new force, thestrong nuclear force

that holds them

together anyway.


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Nuclear NotationNuclear Notation

To keep track of what nucleons an atom has

chemists write their symbols with two

numbers

In any reaction (nuclear or chemical) these

numbers must also balance.

C

12

6

atomic mass = protons + neutrons

atomic number = protons


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Nuclear notation: GenericNuclear notation: Generic

SymbolsSymbols

XA

Z

equired, distinguishes one

sotope from another

Optional, redundant info

With the element symbol

Element symbol

A nuclide can also be written: element-A

carbon 14, is 14 C

uranium 238 is238

U


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Find your Beaker! AndFind your Beaker! And

respond to the following.respond to the following.Write the following atoms in nuclear notationPro/Neu Symbol Atom

4/3 Be Be

12/14 Mg Mg

20/22 Ca Ca

20/24 Ca Ca

43/50 Tc Tc

74

26

12

42

20

44

20

93

43


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Types of RadioactiveTypes of Radioactive

DecayDecayTo balance nuclear reactions we need to include particles with

special names

particle = helium nucleus He

particle = electron e-

positron e+

Neutron n

Proton = hydrogen nucleus H

Gamma Ray

4

2

0

-1

10

1

+1

0+1

00


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Nuclear StabilityNuclear Stability Approx 1,500 different nuclei are known;

about 264 are stable

Elements with N/P ratio = 1:1 are stable

Above atomic number 20, stable nucleihave a higher N/P ratio up to about 1.53:1

Stable nuclei fall within a region called

"band of stability"; if they fall outside area,

they undergo spontaneous radioactive

decay


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Band ofBand of

StabilityStability All nuclei with 84

or more protonsare unstable

Heavy nuclei withtoo many neutronsor too many

protons areunstable

Alpha Decay

Positron emission and/orelectron capture


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Nuclear StabilityNuclear Stability

Nuclei below the zone of stability are likely toundergo:

Positron production, + (too many protons and

not enough neutrons so a proton is converted toa neutron and a positron is emitted)

Electron capture, - (too many protons and not

enough neutrons so a proton is changed into aneutron and an electron is captured in the

process.)


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Alpha particle production (an alphaparticle is released dropping the atomicnumber by 2 and the atomic mass by 4)

Nuclei above the zone of stability are likelyto undergo:

Beta particle production, - (too manyneutrons and not enough protons so anelectron is released as a neutron is

converted to a proton)


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Alpha Particle ProductionAlpha Particle Production


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Gamma rays or rays are producedusually during a decay process that

has emitted an alpha or beta particle.

The gamma ray is a high energyphoton. They almost always

accompany electron captureprocesses to release excess energy.


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Decay of Uranium - 238Decay of Uranium - 238


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Writing Nuclear EquationsWriting Nuclear Equations

Write the nuclear

equation representing thedecay of Potassium 40

as it emits a positron.


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Writing Nuclear EquationsWriting Nuclear Equations

AnswerAnswer

Fi dFi d R di tiR di ti


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Find yourFind your RadioactivemanRadioactivemanand try these HOTand try these HOT

Problems!!Problems!! 11 C produces a positron

214 Bi produces a - particle

237Np produces an particle

Potassium - 40 captures an electron

Potassium - 40 emits a - particle


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More Practice!More Practice!Balance the following nuclear reactions:

Gallium 73 transmutes to germanium-73Platinum -192 transmutes to osmium-188Bombarding alpha particles to anunknown element produces berkelium-243 and a neutronFusion of uranium-238 and carbon-12produces 6 neutrons and what otherelement?


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Alpha Beta Gamma!Alpha Beta Gamma!


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Geiger-Muller CounterGeiger-Muller Counter


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elative Energieselative Energies particles are heavy,

slow, and low energy.They cant penetrate

paper.

particles are small,

fast, and medium

energy. They cant

penetrate foil

rays are photons,have no mass, are fast,

and high energy.

Some may be stopped

by lead.


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Nuclear FissionNuclear Fission


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Nuclear Power PlantNuclear Power Plant


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Nuclear FusionNuclear Fusion

St ll F ti f C bSt ll F ti f C b


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Stellar Formation of Carbon -Stellar Formation of Carbon -

1212


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Effects of a nuclear bomb

1) Explosive Blast

- a lot of pressure makes houses fall down2) Direct Radiation

- radioactive nuclei ejected from the bomb

3) Thermal Radiation

- heat and light that will burn you

4) Radioactive Fallout

- dust and debris are made radioactive, enter the

atmosphere and spread long distances

http://www.pbs.org/wgbh/amex/bomb/sfeature/effects.html


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Plasma Ball of Early AtomicPlasma Ball of Early Atomic

Bomb TestBomb Test


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Plasma Ball of Early Atomic BombPlasma Ball of Early Atomic Bomb

TestTest


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How long doesHow long does

radioactivity stay around?radioactivity stay around?

Every radioactive nucleus has a half life.

This is the amount of time before half of it is gone.


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Half LifeHalf Life

The amount of time it takes for half of the nuclide todecay.Time N

0 100

1 50

2 25

3 12.54 6.25

5 3.125

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