21 Radioactivity

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Presentation slides for GCE O-Level Combined Science 5129 Radioactivity Topic.

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RADIOACTIVITYCombined Science 5129

1

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

What Comes To Mind ... RadiationDANGER

$%*!!Nuclear Bombs!!!

... with the word Radioactivity2

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

BOMBING OF JAPAN

WORLD WAR II, 19453

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NUCLEAR ACCIDENTPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com4

Radioactive materials were released to the environment due to technical malfunction and human error from Nuclear Power Plant.

THREE MILE ISLAND, NEW YORK, 1979

NUCLEAR ACCIDENTPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com5

Explosion & fire at the nuclear power plant released radioactive particles to the environment and spread throughout Europe.

CHERNOBYL, 1986

SCENES FROM CHERNOBLYPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

THE AREA IS STILL HIGHLY RADIOACTIVE AFTER 27 YEARS!6

NUCLEAR DISASTERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com7

A series of equipment failures, nuclear meltdown and release of radioactive materials following the Tohoku earthquake and tsunami.

FUKUSHIMA, JAPAN, 2011

Cosmic Rays Granite Radon Gas Potassium-408

SOURCES OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

SOURCES OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com9

Fall-out from Nuclear Bombs

Nuclear Power Stations

Radioisotopes in medical procedures

SOURCES OF NUCLEAR RADIATION

YOU10

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

DISCOVERY OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

Henri Becquerel( 1852 - 1908 )

Discover spontaneous radioactivity while working with uranium salts in 1896.

The unit of radioactivity is the becquerel (Bq)11

DISCOVERY OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com12

Becquerel crater on the Moon

Becquerel crater on Mars

DISCOVERY OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com13

Marie Curie( 1867 - 1934 )

Introduced the term Radioactivity

Formulated a theory of radioactivity, pioneered techniques for isolating radioactive isotopes, and discovered two new elements, polonium and radium.

The international standard for radioactive emission - the curie (Ci)

Discovered the radioactive elements Radium and Polonium14

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

DISCOVERY OF NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

Radioactive elements in the Periodic Table15

Geiger-Muller Tube

Cloud Chamber Charged Electroscope

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com16

DETECTORS OF NUCLEAR RADIATION

DETECTORS OF NUCLEAR RADIATION

Photographic Films Radiation Badges

17

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Unstable nucleus breaks up, releases tiny particles and waves of energy

Nuclear radiation comes from the centre of unstable atoms.

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com18

ORIGINS OF NUCLEAR RADIATION

Alpha Radiation

Three Types of Nuclear Radiation

Beta Radiation

Gamma Radiation

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com19

TYPES OF NUCLEAR RADIATION

Thinner, wavy tracks Straight, thick tracks

Beta Radiation

Alpha Radiation

Gamma Radiation20

Short, irregular, thin tracks

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

IDENTIFICATION OF NUCLEAR RADIATION USING CLOUD CHAMBER TRACKS

2 protons and 2 neutrons

Alpha Particle Beta Particle Unstable Nucleus Gamma Rays

Same structure as Helium nucleus

High energy, fast-moving electron

High energy, short wavelength, electromagnetic radiation

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com21

NATURE OF NUCLEAR RADIATION

+2 charge

Alpha Particle Beta Particle Unstable Nucleus Gamma Rays

Very strongly ionising

-1 charge Less ionising than alpha particle, more ionising than gamma rays 0 charge Least ionising

Ionising strength tell us whether a particle has the ability to change other substances into ions. Higher charge, Strongly Ionising22

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IONISING STRENGTH OF NUCLEAR RADIATION

Alpha Particle Beta Particle Unstable Nucleus Gamma Rays

Very Weak, Least penetrating radiation

More penetrating than alpha, less penetrating than gamma

Strong, Most penetrating radiation

Penetrating power tell us whether a particle has the ability to go through other substances

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com23

PENETRATING POWER OF NUCLEAR RADIATION

STOPPING NUCLEAR RADIATIONPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com24

Alpha RadiationFew cm of air Thin paper Human skin

Beta Radiation5 mm Aluminium

Gamma RadiationThick lead and few metres of concrete

NUCLEAR RADIATION HAZARDSAlpha Particle Beta Particle Unstable Nucleus Gamma RaysVery hazardous if taken orally / injected into the bodyPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com25

Dangerous, Can penetrate through human skin

Most dangerous, Can penetrate through deep body tissues

Radiation Burns

Leukemia, Cancer, Cell Mutation26

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LOW LEVEL EXPOSURE Delayed Effects Immediate Effects

NUCLEAR RADIATION HAZARDS

NUCLEAR RADIATION HAZARDS

Immediate Death27

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

HIGH LEVEL EXPOSURE

USES OF RADIOACTIVE ISOTOPES

Tracer28

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USES OF RADIOACTIVE ISOTOPES

Radiotherapy Archaeology29

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USES OF RADIOACTIVE ISOTOPESPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com30

Surgical Tools

Food

Thickness Gauge

Sterilization

Using Radioactive Materials

Use tweezers for weak radioactive sources Use remote control equipment for strong & dangerous radioactive sources

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com31

HANDLING RADIOACTIVE MATERIALS

SAFETY PRECAUTIONS

Using Radioactive Materials

Wear special protective clothing & film badges

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com32

HANDLING RADIOACTIVE MATERIALS

SAFETY PRECAUTIONS

Storing Radioactive MaterialsRadiation Symbol Displayed & containers labelled Radioactive Source

Keep in lead containers with walls few cm thick.

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com33

HANDLING RADIOACTIVE MATERIALS

SAFETY PRECAUTIONS

Disposal of Radioactive Materials

Deep in underground/ underwater vaults lined with thick lead-cement walls

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com34

HANDLING RADIOACTIVE MATERIALS

SAFETY PRECAUTIONS

NUCLEAR REACTIONSAlpha Decay Decay Beta Decay Gamma DecayPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com35

Three Types of Nuclear Reactions

Fission

Nuclear Power Plants Nuclear Bombs

Fusion

Formation of Stars & Galaxy Formation of Elements Future Nuclear Power Plants

NUCLEAR DECAYThe breakdown of radioactive unstable nuclei to form stable nuclei of other elements by emitting alpha particles or beta particles.Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com36

RADIOACTIVE DECAY

It is a random process, spontaneous and cannot be controlled.

NUCLEAR DECAYThe average time taken for half the number of atoms in any given sample of a radioactive element to decay.Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com37

HALF-LIFE

The half-life of a sample radioactive isotope can be determined from its decay curve.

First, nd the original value for the activityAverage number of decay per second

Becquerel (Bq)

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com38

HALF-LIFE & DECAY CURVE

NUCLEAR DECAY

Second, nd half of the original value for the activity

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com39

HALF-LIFE & DECAY CURVE

NUCLEAR DECAY

Thirdly, nd the time taken for half of the original value for the activity to happen. This value is the half life of the radioactive sample.

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com40

HALF-LIFE & DECAY CURVE

NUCLEAR DECAY

The half life of a radioactive sample is the same throughout its decay p