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Physics AQA Triple > Atomic Structure and Radioactivity > Flashcards

Atomic Structure and Radioactivity Flashcards

Paper 1 - P3

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1
Q

What is the radius of an atom?

A

1 x 10-¹⁰

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2
Q

Why are some energy levels have higher energy than others?

A

Energy levels which are further from the nucleus are at a higher energy than those which are closer to the nucleus.

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3
Q

How can atoms move between energy levels?

A

-If an atom absorbs electromagnetic radiation an election can move from a lower energy level to a higher energy level.
-Now the atom can emit electromagnetic radiation and the electron returns back to the lower energy level.

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4
Q

What is an isotope?

A

They are atoms of the same element that have different numbers of neutrons.

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5
Q

What did the Ancient Greeks think of atoms?

A

-That everything is made of atoms
-Atoms are tiny spheres which cannot be divided

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6
Q

What did Scientists discover about atoms in 1897?

A

-They discovered that atoms contain tiny negative particles called electrons.
-This showed that atoms are not sphere that cannot be divided.
-Atoms have an internal structure.

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7
Q

What did the plum-pudding model show for the structure of atoms?

A

An atom is a ball of positive charge with negative electrons embedded in it.

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8
Q

What happened in the Alpha-Scattering experiment?

A

-Scientists took a piece of gold foil as it is a few atoms thick.
-Then they fired tiny alpha particles at the gold foil.
-They first saw that most alpha particles passed straight through the foil without changing direction.
-And sometimes an alpha particle was deflected and it changed direction as it passed through the gold foil.
-And other times an alpha particle would simply bounce of the gold foil.

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9
Q

What did scientists find out during the Alpha-Scattering experiment?

A

-That most of the alpha particles went straight through the gold foil therefore meaning atoms are mainly empty space.
-Some of the alpha particles were deflected therefore the centre of an atoms must have a positive charge and that repelled the alpha particles.
-Sometimes an alpha particle bounced straight back therefore the mass of the atoms must be concentrated in the centre called the nucleus.

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10
Q

What did the Plum-pudding model get replaced by?

A

The nuclear model

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11
Q

What did the scientist Niels Bohr propose?

A

-That electrons orbit the nucleus at specific distances.
-Bohr’s work agreed with the results of experiments by other scientists.
-We now call the ‘orbits’ energy levels or shells.

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12
Q

Who discovered that the nucleus contained neutrons?

A

James Chadwick

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13
Q

What is radioactive decay?

A

When some isotopes have an unstable nucleus and to become stable the nucleus gives out radiation.

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14
Q

What is it meant by the activity?

A

The rate at which a source of unstable nuclei decay

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15
Q

How do we measure the activity of a radioactivity source?

A

We can use a Geiger-Muller tube

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16
Q

What is the count-rate?

A

The number of decays recorded each second by a detector

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17
Q

What is an Alpha particle?

A

2 neutrons and 2 protons with a helium nucleus

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18
Q

What is a Beta particle?

A

An electron which is ejected from the nucleus at very high speed.

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19
Q

How is a Beta particle formed?

A

Inside a nucleus when a neutron changes into a proton and an electron.

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20
Q

What is Gamma radiation?

A

A type of electromagnetic radiation from the nucleus

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21
Q

What are the properties of alpha particles?

A

-Alpha particles are large
-They can travel around 5cm in air before they collide with air particles and stop
-Stopped by a single sheet of paper
-Very strongly ionising

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22
Q

What are the properties of beta particles?

A

-Beta particles can travel around 15cm in air before stopping
-Stopped by a few millimetres of aluminium
-Quite strongly ionising

23
Q

What are the properties of gamma radiation?

A

-Gamma radiation travels several meters in air before stopping
-Several centimetres of lead
-Weakly ionising

24
Q

What happens to the atomic number in alpha decay?

A

It decreases by 2

25
Q

What happens to the mass number in alpha decay?

A

It decreases by 4

26
Q

What happens in Beta decay?

A

A neutron changes to a proton and an electron and the electron is ejected from the nucleus that we call a beta particles.

27
Q

What happens to the atomic number in beta decay?

A

It increases by 1

28
Q

What happens to the mass number in beta decay?

A

It does not change

29
Q

What happens in gamma decay?

A

Both the atomic number and the mass number are not changed at all

30
Q

What is the half-life?

A

The time it takes for the number of nuclei of the isotope in a sample to halve.
Also the half-life is also the time it takes for the count rate from a sample containing the isotope to fall to half its initial level.

31
Q

What is irradiation?

A

Irradiation is exposing an object to nuclear radiation (alpha, betta, gamma or neutrons)

32
Q

What can ionising radiation cause?

A

Cancer

33
Q

What do people who work with radioactive isotopes have to do?

A

Take precautions (such as gloves or lead aprons)

34
Q

How can we measure how much radiation has been received?

A

By using a radiation monitor

35
Q

What is contamination?

A

When unwanted radioactive isotopes end up on other materials

36
Q

Why is contamination hazardous?

A

As radioactive atoms decay and emit ionising radiation

37
Q

Why is alpha radiation hazardous with contamination?

A

-Strongly ionising but easily stopped by dead cells on the skin surface
-Alpha emitters can be dangerous if inhaled or swallowed

38
Q

Why is beta radiation hazardous with contamination?

A

-Quite ionising and can penetrate skin into the body

39
Q

Why is gamma radiation hazardous with contamination?

A

-Weakly ionising and can penetrate body but likely to pass straight through

40
Q

(Triple only) What is it meant by background radiation?

A

Background radiation is the radiation that is present all around in the environment.

41
Q

(Triple only) What are some examples of background radiation?

A

-Certain rocks including granite.
-Cosmic rays which are very high energy particles which travel through space and crash into the Earth’s atmosphere.
-Fallout from nuclear weapon testing which release radioactive isotopes into the environment for decades.
-Nuclear accidents are released by accidents at nuclear power stations.

42
Q

(Triple only) How is background radiation affected?

A

By your location and your occupation

43
Q

(Triple only) What is the does of radiation measured in?

A

Sievert (Sv)

44
Q

(Triple only) What are the issues with using a radioactive tracer?

A

-The tracer must emit radiation that can pass out of the body and be detected (beta or gamma radiation).
-The tracer must not be strongly ionising to minimise damage to body tissue.
-The tracer must not decay into another radioactive isotope.
-The tracer must have a short half-life so it is not present in the body for a long period.

45
Q

(Triple only) What is radiotherapy?

A

When certain cancer can be destroyed by using ionising radiation

46
Q

(Triple only) What is a problem with radiotherapy?

A

Healthy tissue may also be damaged as the radiation passes through the body

47
Q

(Triple only) What is an advantage of using radioactive rods to treat prostate cancer?

A

Less damage to healthy tissue as the radiation is targeted very precisely to the tumour

48
Q

(Triple only) What is nuclear fission?

A

When the nucleuses of large and unstable elements split

49
Q

(Triple only) What is the process of nuclear fission?

A

-When a uranium nucleus absorbs a neutron, this triggers they nucleus to undergo fission (split).
-When the nucleus splits, it forms two smaller nuclei roughly equal in size (daughter nuclei).
-This also emits two or three neutrons plus gamma radiation.
-Energy is also released during the fission reaction and all the fission products have kinetic energy.
-The neutrons can now be absorbed by more uranium nuclei and trigger fission again.
-And a chain reaction begins.

50
Q

(Triple only) What can a controlled chain reaction be used for?

A

To release energy in a nuclear reactor

51
Q

(Triple only) What can an uncontrolled chain reaction be used for?

A

To make an explosion in a nuclear weapon

52
Q

(Triple only) What is nuclear fusion?

A

When two light nuclei are joined to form a heavier nucleus

53
Q

(Triple only) What can some of the mass in nuclear fusion be used for?

A

Some of the mass of the nuclei can be converted into energy which is released as radiation

Physics AQA Triple (8 decks)

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