P7(Radioactivity) Flashcards by Rama BRANA

What were the 3 observations from Rutherfords experiment

-Most alpha particles went straight through
-Some alpha particles were deflected at an angle
- very few 1 in 10,000 were deflected at an angle more than 90 degrees

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What were the 3 conclusions from Rutherfords experiment

-Most of the space in an atom is empty
-there is some volume in an atom that is positively charged
-this positive volume is very small

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What is the structure of an alpha particle

2 protons and 2 neutrons

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What is the structure of a beta particle

High energy electron

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What is the structure of gamma radiation

Electromagnetic wave

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What is the charge of an alpha particle

Positively charged

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What is the charge of a beta particle

Negatively charged

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What is the charge of gamma radiation

Neutral

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What is the deflection for an alpha particle

Will be deflected by electric fields by positive side

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What is the deflection for a beta particle

Will be deflected by electric field by negative side

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What is the deflection for gamma radiation

Won’t be deflected by electrical field

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What is the ionising power for an alpha particle

Highly ionising

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What is the ionising power for a beta particle

Less ionising than alpha

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What is the ionising power for Gamma

Least ionising

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What is the penetration power for alpha

Least penetrating only travels few cm in air
-can be stopped by paper

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What is the penetration power for beta

More penetrating than Alpha travels few metres in air
-can be stopped by thin aluminium

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What is the penetration power for Gamma

Infinite distance
-stopped by thick lead and concrete

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What are the uses for alpha radiation

Used in smoke alarms

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What are the uses for beta radiation

Used to monitor thickness of paper or thin aluminium sheets

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What is the uses of Gamma radiation

Used to treat cancer and it’s used to sterilise hospital equipment

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What are the differences from the plum pudding model and nuclear model

-the plum pudding model has negative electrons evenly spaced out
-the plum pudding model has a positively charged sphere
-the nuclear model has negative electrons in random orbits, orbiting the nucleus
-the nuclear model has a nucleus formed of protons and neutrons which makes the nucleus have a neutral charge

How does a smoke alarm work

-Alpha particles ionise air molecules between the charged plates
-Circuit is completed live current through the gap
-smoke particles do not get ionised
-breaks circuit and alarm sound goes off

How is the thickness of the of paper monitored by beta radiation

-For constant thickness count rate does not change
-Increased thickness count rate decreases
-decreased thickness count rate increases
-detector sends message to computer to reset the thickness
-Alpha not suitable because u will not pass through paper
-Gamma not suitable as it will pass through paper unaffected

What is an alpha particle

What happens when an atom loses an alpha particle

The atomic mass number decreases by 4 -The proton number decreases by 2

What is a beta particle

What happens to an atom when beta(-) decay occurs

The atomic mass number remains the same -The proton number increases by 1

What is radioactivity

The process in which radioactive elements decay by giving out alpha,beta or gamma radiation

What is count rate(Activity)

Number of atoms decaying per unit time

What is the formula for count rate(Activity)

Which radioactive isotope will be most suitable for medical treatment

half life of tracer must be such that it lasts till the tests have been completed -decay almost completely after the tests -decay into a stable product -least ionising so it doesn’t damage living cells -highly penetrating enough to reach detectors -Gamma is most suitable

What is nuclear fission

Process in which a larger unstable nucleus splits into 2 smaller and stable nucleus, 2 or 3 neutrons and a large amount of energy

Diagram of nuclear fission

What are the components of a nuclear reactor

Fuel rods- made up of fissionable material Control rods-made up of boron absorbs neutrons to slow down the process or shut it down Moderator-made up of heavy water Shielding- Around the nuclear reactor made from concrete and lead, prevent leak of nuclear radiation

What is nuclear fusion

Process in which 2 smaller nuclei fuse together to form larger nucleus and large amount of energy

How does nuclear fusion work

-When 2 protons fuse together they form a Heavy hydrogen nucleus -two more protons collide with the heavy hydrogen nucleus turning the nuclei into heavier nuclei -the 2 heavier nuclei collide to form the helium nucleus

What are the advantages of nuclear fusion

-large amounts of energy produced -no harmful gases produced -hydrogen is a raw material is abundant -no nuclear waste produced -byproduct is helium gas which is unreactive

What is disadvantages of nuclear fusion

-Technology is still in early stages of development -energy to extract hydrogen may be taken from fossil fuels -large amounts of energy is needed to initially start nuclear fusion

Comparing fission with fusion

Fission: -larger nucleus splits into 2 smaller stable nuclei -2 or 3 neutrons are produced -energy released in form of gamma radiation -a slow moving neutron hits unstable nucleus -nuclear waste is produced -technology is well known Fusion: -2 smaller nuclei fuse to form larger nucleus -no neutron produced -energy released in form of gamma radiation -large amounts of initial energy is needed -no nuclear waste produced -technology is in early stages

How does nuclear fission work

a slow moving neutron hits a large unstable nucleus -larger nucleus splits into 2 smaller stable nuclei -2 or 3 neutrons are produced -chain reaction is created as the neutrons emitted hit other unstable nuclei -energy released in form of gamma radiation