RadioactivityRadioactivity
Chapter 9Chapter 9
Nuclear ChangesNuclear Changes
RadioactivityRadioactivity
Radioactive materials Radioactive materials have unstable nuclei.have unstable nuclei.
They emit They emit particles/energy to particles/energy to become stable. become stable.
Isotopes are generally Isotopes are generally radioactive. Why do radioactive. Why do you think that is?you think that is?
Four Different Types of Four Different Types of RadioactivityRadioactivity AlphaAlpha
Protons and Neutrons Protons and Neutrons are emittedare emitted
BetaBeta 1 electron is emitted1 electron is emitted
GammaGamma Light is emittedLight is emitted
NeutronNeutron Neutrons are emittedNeutrons are emitted
So Why Is It Dangerous?So Why Is It Dangerous? It’s not ALWAYS It’s not ALWAYS
dangerous, but most of dangerous, but most of the time it is.the time it is.
The energy/particles that The energy/particles that are emitted travel are emitted travel through the air and hit through the air and hit the atoms it meets. This the atoms it meets. This disturbs the atoms.disturbs the atoms.
Do you think you want Do you think you want disturbed atoms in your disturbed atoms in your body?body?
How Do We Prevent too How Do We Prevent too much Radiation Exposure??much Radiation Exposure?? Shielding!Shielding! Shielding is the materials that Shielding is the materials that
are between the radioactive are between the radioactive source and the detector or source and the detector or person.person.
The purpose of shielding is to The purpose of shielding is to reduce the amount of radiation reduce the amount of radiation that one person or object that one person or object receives.receives.
ShieldingShielding
Alpha particlesAlpha particlesStopped by paper or the skinStopped by paper or the skinPresent little or no hazard external to Present little or no hazard external to
bodybodyInternal hazard (if it gets in the body)Internal hazard (if it gets in the body)
Beta particlesBeta particlesStopped by light metals (aluminium) Stopped by light metals (aluminium)
and plasticsand plasticsInternal and external hazardInternal and external hazard
ShieldingShielding Gamma raysGamma rays
Stopped by very dense materials Stopped by very dense materials (lead, concrete)(lead, concrete)
Easily pass through the human bodyEasily pass through the human body Internal and external hazardInternal and external hazard
NeutronsNeutronsStopped by materials containing Stopped by materials containing
hydrogen atoms, such as water, hydrogen atoms, such as water, polyethylene, and concretepolyethylene, and concrete
Internal and external hazardInternal and external hazard
Shielding: Alphas, Betas, Shielding: Alphas, Betas, Gammas and NeutronsGammas and Neutrons
Where Does the Where Does the Radiation Come From?Radiation Come From?
The radiation you receive can be either The radiation you receive can be either Natural or Man-madeNatural or Man-made
Sources of Radiation: Sources of Radiation: Natural Natural Cosmic: Cosmic:
Sun Sun
Terrestrial: sources in the earth’s Terrestrial: sources in the earth’s crustcrust
Soil (radon)Soil (radon)WaterWaterVegetation (Bananas)Vegetation (Bananas)
Internal: sources in the human Internal: sources in the human bodybody
Potassium-40Potassium-40Carbon-14Carbon-14Lead-210Lead-210
Sources of Radiation: Sources of Radiation: Man-madeMan-made MedicalMedical
X-raysX-rays Cancer treatmentsCancer treatments
CommercialCommercial TVTV Lantern mantelsLantern mantels Smoke detectorsSmoke detectors Fuel cycle (nuclear power)Fuel cycle (nuclear power)
Determining Your Determining Your Personal Annual Personal Annual Radiation DoseRadiation Dose
Average Annual Dose to Average Annual Dose to Ionizing RadiationIonizing Radiation
All living creatures constantly receive a All living creatures constantly receive a certain amount of radiation from outer certain amount of radiation from outer space, the soil, food we ingest or even space, the soil, food we ingest or even the air we breathe. the air we breathe.
The sources of radiation fall under two The sources of radiation fall under two categories: natural and man-made, categories: natural and man-made, collectively known as collectively known as background background radiationradiation. .
The The averageaverage annual personal dose from annual personal dose from background radiation is approximately background radiation is approximately 350350 mRem/year. mRem/year.
What To DoWhat To Do In this activity, you will estimate your In this activity, you will estimate your
personal annual radiation dose using the personal annual radiation dose using the Background Information Worksheet provided. Background Information Worksheet provided. When doing this activity, keep in mind that When doing this activity, keep in mind that the amount of the amount of terrestrial radiation varies in different parts terrestrial radiation varies in different parts
of the world due to different concentrations of the world due to different concentrations of uranium and thorium in soil. of uranium and thorium in soil.
cosmic radiation varies in different parts of cosmic radiation varies in different parts of the world due to differences in elevation the world due to differences in elevation and to the effects of the earth’s magnetic and to the effects of the earth’s magnetic field.field.
ProcedureProcedure Complete the worksheet and tally the total.Complete the worksheet and tally the total. For central Ohio, the average elevation is about 825 For central Ohio, the average elevation is about 825
feet above sea levelfeet above sea level approximate dose is 28 mRem/year from cosmic radiation.approximate dose is 28 mRem/year from cosmic radiation.
For every hour in an airplane, you receive 0.5 mRem For every hour in an airplane, you receive 0.5 mRem Make sure to use 30 mRem/year for the second Make sure to use 30 mRem/year for the second
entry.entry. In central Ohio, we are not within 50 miles of a In central Ohio, we are not within 50 miles of a
power plant. However in southern Ohio, there are power plant. However in southern Ohio, there are many coal plants along Ohio River.many coal plants along Ohio River.
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