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PHYSICS > ATOMIC STRUCTURE > Flashcards

ATOMIC STRUCTURE Flashcards

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1
Q

What is the mass number?

A

Protons and neutrons

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2
Q

What is the atomic number?

A

Protons/electrons

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3
Q

What is an isotope?

A

Same atomic number and charge
Different mass number (neutrons)

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4
Q

What happens if an isotope is unstable?

A

It tends to decay into other elements and give out radiation as they try to become more stable (radioactive decay)

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5
Q

What can be the products of radioactive decay?

A

Neutrons (trying to stabilise)
Alpha, beta and gamma radiation

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6
Q

What is an alpha particle?

A

Like a helium nuclei
Two protons and two neutrons

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7
Q

What is alpha radiation?

A

When an alpha particle is emitted from the nucleus

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8
Q

What are the characteristics of alpha radiation?

A

Don’t penetrate very far into materials and are stopped quickly
Strongly ionising

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9
Q

What can alpha radiation be stopped by?

A

Skin/sheet of paper

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10
Q

What is a beta particle?

A

A fast-moving electron
No mass and a charge of -1

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11
Q

What are the characteristics of beta radiation?

A

Penetrate moderately far into materials before colliding
Moderately ionising

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12
Q

What can beta radiation be stopped by?

A

Sheet of aluminium (around 5mm)

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13
Q

What happens during beta radiation?

A

For every electron emitted, a neutron is turned into a proton

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14
Q

What are gamma rays?

A

Waves of electromagnetic radiation released by the nucleus

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15
Q

What are the characteristics of gamma rays?

A

They penetrate far into materials without being stopped
Weakly ionising (pass through rather than collide with atoms)

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16
Q

What can gamma rays be stopped by?

A

Thick sheets of lead or concrete

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17
Q

What are nuclear equations?

A

They show radioactive decay
Mass and atomic number have to balance

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18
Q

How do you set out nuclear equations?

A

atom before decay —> atom after decay + radiation emitted

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19
Q

What happens during alpha decay (nuclear equation)?

A

An atom emits an alpha particle so it’s mass number reduces by 4 and it’s atomic number reduces by 2

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20
Q

Which number is mass and atomic?

A

Mass number
then
Atomic number

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21
Q

What happens to the charge of an atom after alpha decay?

A

The charge decreases because it lose two protons (+)

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22
Q

What happens during beta decay?

A

A neutron in the nucleus turns into a proton and releases a fast-moving electron (beta particle)

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23
Q

What happens to the charge of an atom after beta decay?

A

A neutron has been turned into a proton so the charge increases

24
Q

What happens to the mass and atomic number of an atom after beta decay?

A

The atomic number increases because one new proton has been made
The mass number stays the same because a proton has been made and a neutron has been lost

25
Q

What do gamma rays do during decay?

A

They get rid of excess energy from a nucleus so no change to atomic or mass number of an atom

26
Q

How can radiation be measured?

A

By using a Geiger-Muller tube and counter to record count-rate

27
Q

What is half life?

A

The time it takes for the number of radioactive nuclei in an isotope to halve

28
Q

What happens each time a radioactive nucleus decays to become stable?

A

The activity will decrease

29
Q

What can half life be used to find?

A

The rate at which a source decays (1 becquerel Bq = 1 decay per second)

30
Q

What does a short half life mean?

A

Activity falls quickly because nuclei are very unstable and rapidly decay (dangerous because emit high amounts of radiation)

31
Q

What does a long half life mean?

A

Activity falls more slowly because most of the nuclei don’t decay for a long time (can be dangerous because nearby areas exposed to radiation for years)

32
Q

What is background radiation?

A

Low level radiation that’s around us all the time
REMEMBER TO SUBTRACT FROM RESULTS

33
Q

What are cosmic rays?

A

Radiation from the sun

34
Q

What are examples of naturally occurring radiation?

A

Rocks
Food
Building materials
Air

35
Q

What is an example of radiation due to human activity?

A

Fallout from nuclear explosions or waste

36
Q

How many Sv = mSv

A

1Sv = 100mSv

37
Q

What is radiation dose measured in?

A

Sv (sieverts)

38
Q

What does radiation dose tell you?

A

The risk of harm to body tissues due to exposure to radiation

39
Q

What is irradiation?

A

Exposure to radiation

40
Q

How can you stop irradiation occurring?

A

Keep sources in lead-lined boxes
Stand behind barriers
Be in a different room
Use remote controlled arms

41
Q

When is an object considered contaminated?

A

If an unwanted radioactive atom gets onto or into an object

42
Q

How do you stop contamination occurring?

A

Wear gloves
Use tongs
Protective suits

43
Q

Why are beta and gamma radiation the most dangerous outside the body?

A

Because they can penetrate the body and get to delicate organs
(Alpha cannot penetrate the skin)

44
Q

Why is alpha radiation the most dangerous inside the body?

A

Because they cannot pass back out through the skin and do damage in very localised areas

45
Q

Why is beta and gamma radiation least damaging inside the body?

A

Because they can pass out of the body and have lowish ionising power

46
Q

Why is radiation a risk to humans?

A

It can enter living cells and ionise atoms and molecules which can lead to tissue damage (can kill cells)

47
Q

How can radiation be used as medical tracers?

A

Injected or swallowed
External detector can monitor their progress around the body (usually gamma and never alpha)

48
Q

What radiation should be used in medical tracers?

A

Gamma so can exit the body without causing much damage
Short half life so radiation quickly disappears

49
Q

How can radiation be used to treat cancer?

A

Gamma rays directed carefully and at just the right dosage to kill cancer cells without damaging too many normal cells

50
Q

What is nuclear fission?

A

Nuclear reaction that is used to release energy from large and unstable atoms

51
Q

What happens during nuclear fission?

A

Atom splits to form two new lighter elements
Two or three neutrons are also released which can cause more fission to occur if they are absorbed by another nucleus

52
Q

What happens to the energy not transferred to the kinetic energy stores during nuclear fission?

A

It is carried away by gamma rays

53
Q

What is nuclear fusion?

A

The joining of two small nuclei

54
Q

What happens during nuclear fusion?

A

Two light nuclei collide at high speed and fuse together to create a larger heavy nucleus

55
Q

What happens to the mass during nuclear fusion?

A

Some mass of the lighter nuclei is converted into energy therefore the heavier nucleus weighs less than the two nuclei before

56
Q

Which releases more energy: fission or fusion?

A

Fusion

57
Q

What is the order of the model of the atom?

A

Atomic model - Dalton
Plum pudding model - Thomson
Nuclear model - Rutherford
Planetary model - Bohr

PHYSICS (12 decks)

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