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Physics > P7 : Radioactivity > Flashcards

P7 : Radioactivity Flashcards

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1
Q

What is Brownian motion?

A
  • random motion of tiny particles in a fluid
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2
Q

Who and what was the nuclear model first discovered?

A

JJ THOMPSON
- electrons were thoughts to be embedded in a positively charged lump of mass
-PLUM PUDDING MODEL

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3
Q

What did RUTHERFORD discover about the structure of atoms?

A
  • most alpha particles went through GOLD FOIL
  • HE FOUND most particles PASSED straight through foil - shows atom is EMPTY SPACE

-small no. alpha particles DEFLECTED TO SIDE - shows + charge located in small space

  • some particles bounced straight back - suggest + charge/mass is CONCENTRATED IN SAMLL SPACE
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4
Q

WHAT was Rutherford’s conclusion after gold foil experiment?

A
  • atom is like a solar system
  • most mass/+ charge in small space in centre
  • electrons orbit around centre
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5
Q

How did they discover NEUTRONS?

A

JAMES CHADWICK
- knew that mass of nucleus is bigger than tootle mass of protons , so must be UNCHARGED TWIN
- THE NEUTRON

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6
Q

what is a nuclide ?

A

a nucleus with different no. NEUTRONS

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7
Q

what does it mean by ‘radioactive’?

A
  • they are UNSTABLE and give out RADIATION at random intervals IN A PROCESS CALLED ‘RADIOACTIVE DECAY’
    • radioactivity is random - decay happens with a CERTAIN PROBABILITY
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8
Q

What is the amount of RADIOACTIVE DECAYS PER SECOND called ?

A

the ACTIVITY of a sample
- measure in BECQUERELS (Bq)

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9
Q

2 ways to detect RADIOACTIVITY?

A

GEIGER MULLER TUBE
PHOTOGRAPHIC FILM

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10
Q

what is alpha radiation?

A
  • atoms decay INTO NEW TYPE OF ATOM and EMITS APLHA PARTICLE
  • Alpha particles have 2 protons/2 neutrons ( HELIUM ATOMS)
  • ALPHA happens when nucleus HAS TOO MANY PROTONS
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11
Q

what is BETA radiation?

A
  • when NEUTRON turns into PROTON/ELECTRONS
    -fast moving , high energy electron is called a BETA PARTICLE
  • Beta happens when NUCLEUS HAS TOO MANY NEUTRONS
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12
Q

what is GAMMA RADIATION?

A
  • very high energy LIGHT , with very high FREQUENCY , VERY SHORT WAVELENGTH
  • atom IS NOT changed by emitting light
  • Gamma happen when parent nucleus has too MUCH electromagnetic energy
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13
Q

what is the charge, mass , penetration ability, range in air, and ionising ability of ALPHA, BETA AND GAMMA?

A

ALPHA. BETA GAMMA
+2. -1 0
4 0 0
LOW MEDIUM. HIGH
few cm 1m infinite
high. medium low

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14
Q

what is HALF LIFE?

A
  • time taken for Half of the radioisotopes in a sample to DECAY.
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15
Q

how is a radiation used in MEDECINE?

A

TRACERS
small amounts of radioactive material used to detect GAPS OR BLOCKAGES
Gamma used bc of low ionising ability and high penetration ability
- SHORT HALF LIFE

RADIOTHERAPY
- high energy gamma radiation can be used to destroy cancer cells, but have to make sure it doesn’t damage other tissues

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16
Q

what is SPONTANEOUS FISSION?

A

very large nuclei need extra NEUTRONS to stop PROTONS from repelling nucleus apart

17
Q

what is INDUCED FISSION?

A

can be made to split up by absorbing a NEUTRON , destabilising the nucleus , causing it to SPLIT IN HALF.

18
Q

WHAT IS FUSION?

A

under extremely high temps/pressure , tow protons can be fused together - continue until helium is made

19
Q

what is nuclear fission?

A

the splitting of a large, unstable nucleus into two smaller nuclei

20
Q

what is count rate?

A

number of decays recorded each second by a detector.

21
Q

explain the process of nuclear fission. (4)

A
  • neutrons are absorbed by a nucleus
  • nucleus splits into 2 daughter nuclei
  • releasing gamma rays
  • and 2/3 neutrons
22
Q

Why is does the food not become become radioactive after being irradiated?

A
  • because it only come in contact with radiation not with isotope itself
23
Q

Ways to protect against radiation?

A
  • lead apron
  • gloves for alpha
  • lead walls
  • radiation monitor can measure how much is received by person
24
Q

Why is radiation contamination dangerous ?

A
  • the radioactive isotopes end up on materials so becomes RADIOACTIVE
  • they decay and emit ionising radiation
25
Q

What is meant by precise results?

A
  • how close measurements are (small variation in results)
26
Q

Name or nuclear fuel

A

Uranium

27
Q

How does the process of nuclear fusion lead to release of energy?

A

Lighter nuclei form heavier nuclei
Some mass converted to energy

28
Q

Advantage of radioactive waste having shorter half life

A

Activity decreases quickly
- risk of harm decreases quickly

29
Q

why take repeat reading ?

A
  • calculate mean
  • reduce effect of random errors
30
Q

risk of short harlf life?

A
  • nuclei will decay very quickly, emiitting alot of radiation in short period of time (COUNT RATE DECREASES QUICKLY)
31
Q

benefit and risk of long half life?

A

BENEFIT : decay slowly, so not asmuch radiation emitted (COUNT RATE IS CONSTANT)

RISK - remain radoactive for long time , so more risk of contamination

Physics (11 decks)

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