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Physics > P7- Radioactivity > Flashcards

P7- Radioactivity Flashcards

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1
Q

What do radioactive substances contain

A

Unstable nuclei that become stable by emitting radiation randomly

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2
Q

Isotope

A

Atoms with the same number of protons, different number of neutrons

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3
Q

Describe the five scientists and discoveries in order

A

Dalton, invisible objects
Thomson, plum pudding model
Rutherford, nuclear model and nucleus
Bohr, electron shells
Chadwick, neutrons and protons

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4
Q

3 main types of radiation

A

Alpha
Beta
Gamma

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5
Q

Chadwick’s model

A

Proton-neutron model
Discovered neutrons

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6
Q

Bohr’s model

A

Introduced electron shells. In line with Rutherford’s discovery

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7
Q

Why was Thomson’s model no longer accepted?

A

His plum pudding model had no nucleus, only electrons in a positive cloud. Rutherford discovered the nucleus

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8
Q

Atomic number
Mass number

A

Number of protons in nucleus
Number of protons plus neutrons in the nucleus

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9
Q

Alpha particle experiment
Who?
What happened?
What did it prove?

A

Rutherford fired alpha particles at thin gold foil
Particles scattered and some reflected back
Proved tiny, massive, positive, central nucleus

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10
Q

Alpha particle
Description?
Charge?
Relative atomic mass?

A

2 protons, 2 neutrons, no electrons
2+
4

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11
Q

Alpha particle
Penetration?
Ionising effect?
Uses?

A

Stopped by single piece of paper, few cm in air
Strong
Smoke detectors

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12
Q

Beta particle
Description?
Charge?
Relative atomic mass?

A

Neutron splitting to 1 proton, 1 electron, electron emitted
-1 No mass

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13
Q

Beta particle
Penetration?
Ionising effect?
Uses?

A

Stopped by mm of aluminium, few m in air
Moderate
Determine thickness of paper

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14
Q

Gamma rays
Description?
Charge?
Relative atomic mass?

A

Waves of electromagnetic radiation
No charge or mass

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15
Q

Gamma ray
Penetration?
Ionising effect?
Uses?

A

Stopped by thick lead, few km in air
Weak
Detect leaks in pipes

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16
Q

Activity definition
Unit and measuring device?

A

Number of decays per second, bequerels (Bq)
Geiger Muller tube

17
Q

Alpha particle calculations
Mass and atomic number

A

Mass number= decreases by 4
Atomic number= decreases by 2

18
Q

Beta particle calculations
Mass and atomic number

A

Mass number= stays same
Atomic number= increases by 1

19
Q

Half life

A

The time it takes for the activity to fall to half it’s starting level

20
Q

Half life equation

A

Count rate after n years= initial count/ 2 to the power of n

21
Q

Nuclear fission

A

The process of splitting atomic nuclei, can be used to produce energy for electricity

22
Q

4 Steps to nuclear fission process

A

1.Neutron absorbed by nucleus
2. Nucleus splits into 2 daughter nuclei
3. Produces energy and 2 or 3 neutrons
4. Happens in chain reaction

23
Q

What are the two uses of radiation in medicine

A

Diagnosis- explanation of internal organs
Treatment- control or destruction of unwanted tissue

24
Q

Radioactive tracer
How?
Use?
What type?

A

Eating or injecting a harmless radioactive material
To trace a substance through an organ
Gamma, detected outside body, low harm

25
Q

Radiotherapy
How?
Use?
What type?

A

High doses of gamma rays
Kills cancerous cells
Gamma, high penetration

26
Q

Radioactive implants
How?
Use?
What type?

A

Small pellets in body
Kills cancer cells over time
Beta or gamma with short half-lives

27
Q

Safety precautions of ionisation

A

Limit time, increase distance, use shielding

28
Q

Contamination

A

A radioactive isotope in other materials

29
Q

Irradiation

A

Exposing an object to radiation

30
Q

Examples of contamination

A

Fish living in the sea around a nuclear power plant
Breathing in radon gas
Drinking tea with radioactive atoms

31
Q

Examples of irradiation

A

Treating fruit with gamma rays to kill bacteria
Sterilising surgical instruments

32
Q

Factors of contamination

A

Radioactive source is on or in the object
Difficult to remove all contamination
Radiation can’t be blocked

33
Q

Factors of irradiation

A

Object is exposed to radiation
Stops as soon as the source is removed
Can be blocked with shielding

34
Q

Nuclear fusion

A

Two nuclei fuse together to make a heavier nucleus

35
Q

4 Steps to nuclear fusion in stars process

A
  1. 2 hydrogen nuclei fuse together
  2. Forms a helium nucleus
  3. Releases energy
  4. Need high temp and pressure
36
Q

5 feature of nuclear fusion

A

Uses Hydrogen as fuel
Joining of two atoms
Takes place in the sun
Fuel is easily available
Needs high pressure
and temp

37
Q

5 features of nuclear fission

A

Uses Uranium as fuel
Splitting of an atom
Causes chain reaction
Often used on earth
Produces nuclear waste

38
Q

2 similarities of nuclear fusion and fission

A

Produces energy
Have been used in a bomb

Physics (13 decks)

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