36883304 radioactivity

8/6/2019 36883304 Radioactivity

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RADIOACTIVITY

Prepared by:

Nurasfiqah Abd Karim

Class:

5 Science11

Teacher:

Miss Nurul Ain binti Nawi


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NUCLEUS

OF AN

ATOM


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THE COMPOSITION OF THE NUCLEUS

A nucleus consists of a number of protons and neutrons. Proton and neutrons are collectively referred

to as nucleon as they are found in the nucleus.

PROTON AND NUCLEON NUMBERS

The proton number, Z, is defined as the number of protons in the nucleus.

The nucleon number, A, is defined as the number of protons and neutrons in a nucleus.

The number of electron is equal to the number of proton.


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NUCLIDE

AZX

A = nucleon number

Z = proton number

X = chemical symbol for the element

ISOTOPE

Isotopes are atoms with the same proton number but different nucleon number.

They have identical chemical properties since they have the same number of electrons.


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RADIOACTIV

E

DECAY


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RADIOACTIVITY

Radioactivity is the spontaneous and random disintegration of an unstable nucleus accompanied by the

emission of energetic particles or photons.

TYPE OF RADIATION ALPHA PARTICLE BETA PARTICLE GAMMA RAY

SYMBOL

MASS 4 1/2000 0

CHARGE +2e -e 0

SPEED Slow Fast Very fast

IONISING ABILITY High Medium Low

PENETRATING POWER Low Medium High

STOPPPED BY A few cm of air or a

piece of paper

A few mm of aluminum

foil

A few cm of lead

DEFLECTED BY

ELECTRIC AND

MAGNETIC FIELDS

Yes Yes No


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DETECTORS OF RADIOACTIVE EMISSION

1. Geiger-Muller tube (GM tube)2. Photographic film3. Gold leaf electroscope4. Cloud chamber5. Bubble chamber

1

5

4

32


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RADIOACTIVE DECAY

Alpha decay

Alpha decay is a radioactive process in which a particle with two neutrons and protons is emitted from

the nucleus of a radioactive atom. Only occurs in very heavy elements such as uranium, thorium and

radium.

Beta decay

Beta particles are electrons emitted by the nucleus. However, the nucleus contains no electron. Beta

decay occurs when a neutron is changed to a proton within a nucleus. As a result, nucleus with N

neutrons and Z protons becomes a nucleus of N-1 neutrons and Z+1 proton after emitting a beta

particles.


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The half-life of a radioactive substance can be determined from a graph of count rate against time.

RADIOISOTOPES


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Radioisotopes are isotopes of an element that are radioactive.

Most of it are created artificially.

ELEMENT HALF-LIFE RADIATION EMITTED

Hydrogen 12.3 years

Carbon 5730 years

Iodine 8.07 days ,

Polonium 0.7 seconds

Uranium 138 days ,

APPLICATIONS OF ISOTOPES

In industries:

1. Smoke detectors2. Thickness control3. Checking welds

In medical fields:

1.

Sterilizing2. Radioactive tracers3. Cancer treatment

In archeology:

1. Radioactive dating


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NUCLEAR

ENERGY


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NUCLEAR FISSION

Nuclear fission is a process in which a heavy nucleus splits into two or more lighter nuclei.

Nuclear fission differs from radioactive decays in three ways:

y The nucleus is divided into two large fragments of roughly equal massy There is a significant mass defecty Other neutrons are emitted in the process

CHAIN REACTION

One neutron starts the fission process, but three neutrons are produced. In this way, a chain is

produced. For a continuous chain reaction to be maintained, a certain critical mass must not be

exceeded. If exceeded, an uncontrolled reaction will occur resulting in an explosion.


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MANAGEMENT OF

RADIOACTIVE

SUBSTANCES


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NEGATIVE EFFECTS OF RADIOACTIVE SUBSTANCES

Effects of radiation on biological systems can be categorized as :

y Acute effects from a single large overexposure of radiation on all the organs and systems of thebody.

y Delayed effects from a single large dose or continuing low-level dose of radiation.

HANDLING RADIOACTIVE SUBSTANCES

Special procedures must be followed when handling radioactive substances. In general,

y Appropriate dosemeters (special film badges to monitor radiation exposures) should be worn bythose working with radioactive substances.

y Workers should handle the radioactive materials remotely with the helps of robotsy Protective clothing such as specially designed gloves, coats, and safety glasses should be worn.y All works areas, equipment and clothing should be routinely checked for contaminationy All radioactive substances should be stored in specially designed containers with clear labels.

MANAGEMENT OF RADIOACTIVE WASTE

Radioactive waste is divided into three broad categories:

y High-level waste includes spent fuel from nuclear power plants and fission products from fuelreprocessing which emit enormous amount of heat

y Intermediate-level waste includes waste products that require handling and shielding but whichdoes not emit significant amount of heat


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36883304 radioactivity

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