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Physics IGCSE > Unit 5 - Nuclear physics > Flashcards

Unit 5 - Nuclear physics Flashcards

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1
Q

Mass and charge of a proton

A
  • 1
  • +1
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2
Q

Mass and charge of a neutron

A
  • 1
  • 0
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3
Q

Mass and charge of an electron

A
  • 1/2000
  • -1
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4
Q

Ernest Rutherford’s alpha particle experiment setup

A
  • Beam of alpha particles directed through a slit in a circular fluorescent screen towards a piece of thin gold foil
  • Carried out in a vacuum so alpha particles wouldn’t collide with anything else
  • A flash would be produced when the alpha particles hit the screen showing their position
  • Most particles travelled through the foil but some were deflected
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5
Q

Rutherford’s findings from his experiment & proof

A
  • Number of protons and electrons are equal - atoms don’t have an overall charge
  • Most of the atom is empty space or nucleus is incredibly small - Most particles went straight through the foil and only 1/8000 were deflected
  • The nucleus is positively charged - Alpha particles are positive some were repelled
  • The nucleus accounts for nearly all the mass - some particles deflected back in the opposite direction, hence the tiny nucleus contains most of the mass to cause that change in momentum
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6
Q

Subatomic particles

A
  • Proton
  • Electron
  • Neutron
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7
Q

Nuclide

A

An atom of nucleus characterized by a specific number of protons and neutrons

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8
Q

Nuclide notation

A
  • Symbol of the element from the periodic table with the nucleon number on the top left and the proton number on the bottom left
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9
Q

Isotopes

A

Atoms of the same element with the same number of protons and electrons but with a different number of neutrons

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10
Q

Nuclear fusion

A

The process by which lighter nuclei collide with high energy and join to form a larger nucleus and energy is released

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11
Q

Nuclear fission

A

Due to the instability of a nuclei with a large nucleon number, it breaks apart either completely independently or if a neutron is fired into the large nucleus making is break and energy is released

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12
Q

Source of released energy in nuclear fission and fusion

A

A decrease in mass (usually -0.1%)

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13
Q

Equipment used to measure radiation

A
  • Geiger-Müller tube - can detect alpha and beta particles and gamma radiation
  • Spark counter - can detect alpha, beta, and gamma radiation
  • Cloud chamber - shows the path of alpha and beta particles by producing a vapor in the trail
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14
Q

Unit of measurement for radioactive decay

A
  • Count rate - number of emissions of radiation in a certain time - (count/s) or (count/min)
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15
Q

Count rate equation

A

Count rate (count/s) = measured count rate (count/s) - background radiation (count/s)

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16
Q

Largest source of background radiation on earth

A

Radon gas

17
Q

Radioactivity

A

The process by which an unstable nucleus becomes more stable by emitting radiation

18
Q

Properties of alpha particles

A
  • Made of two protons and two neutrons
  • Mass of 4
  • Charge of +2
  • Highly ionizing
  • Least penetrating radiation
  • Can only travel 5cm through air and can be stopped by thin paper or skin
  • Attracted by negative and is deflected by a small amount
  • Direction of the particle is equal to the direction of the current
19
Q

Properties of beta particles

A
  • High-energy electron
  • Mass of 1/2000
  • Charge of -1
  • Mildly ionizing
  • Can travel through skin but are stopped by a few mm of aluminum foil
  • Attracted to positive and if deflected by a large amount
  • Direction of the particle is opposite to the direction of the current
20
Q

Properties of gamma emissions

A
  • Electromagnetic waves
  • Very high frequency and very high energy
  • No mass and no charge
  • Weakly ionizing
  • Most penetrating, can only be stopped by thick lead or concrete
  • Path is not altered by an electric field
21
Q

Ionizing radiation

A

Able to strip away the electrons of a material that it comes into contact with

22
Q

Radioactive decay

A

When a nucleus emits alpha or beta particles of gamma radiation in order to become more stable - the decay is spontaneous and in a random direction - nucleus changes to a different element after emission

23
Q

Effect of an emitted alpha particle on a nucleus

A

Loses two protons and hence reduces atomic number by 2

24
Q

Effect of an emitted beta particle on a nucleus

A

Neutron transforms into a proton raising the atomic number

25
Q

Effect of emitted gamma radiation on a nucleus

A

No effect / nucleus remains unchanged

26
Q

Rule of nuclear decay equations

A

Total mass if conserved

27
Q

Half-life

A
  • The time taken for the count rate of a radioactive source to decrease by half / for the number of radioactive nuclei to decrease by half
28
Q

Uses of alpha, beta and gamma radiation

A
  • Food is irradiated with beta or gamma radiation to kill bacteria - increases shelf life
  • Alpha particles are used in smoke detectors - smoke collides with alpha particles so less current flows between positive and negative plates causing an alarm to sound
  • Beta particles are used to test and control thickness of materials
  • Gamma radiation is used in medical tracers
  • Gamma radiation is used on a single point in the body for cancer treatment - can kill cancer cells
  • Gamma rays can be used to sterilize equipment by killing viruses
29
Q

Safety equipment when dealing with radiation

A
  • Lead shield
  • Gloves
  • Glasses or goggles
  • Tongs when moving materials
30
Q

Storing alpha particles

A
  • Thin package
  • Protective clothing must be worn when handling
31
Q

Storing beta particles

A
  • Stored in lead or a similarly dense metal container
32
Q

Storing gamma radiation

A
  • Buried deep underground
33
Q

Safety strategies with radioactivity

A
  • Exposure time - reduce exposure time
  • Shielding - placing a barrier between the person and the radiation
  • Distance - increasing the distance from the source reduces intensity

Physics IGCSE (6 decks)

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