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Physics: P2 > P2.5 What happens when radioactive substances decay, and the uses and dangers of their emmisions > Flashcards

P2.5 What happens when radioactive substances decay, and the uses and dangers of their emmisions Flashcards

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1
Q

What is the basic structure of an atom?

A

A small central nucleus composed of protons and neutrons, surrounded by electrons

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2
Q

What is the relative mass of a proton?

A

1

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3
Q

What is the relative mass of a neutron?

A

1

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4
Q

What is the relative mass of an electron?

A

Very small

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5
Q

What is the relative charge of a proton?

A

+1

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6
Q

What is the relative charge of a neutron?

A

0

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7
Q

What is the relative charge of a electron?

A

-1

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8
Q

In an atom what is the number of electrons equal to?

A

The number of protons in the nucleus

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9
Q

What is the overall charge of an atom?

A

0

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10
Q

How do atoms become ions?

A

They may gain or lose electrons

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11
Q

What is an isotope?

A

When an atom has a different number of neutrons

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12
Q

Can you have different numbers of protons in an atom?

A

No it is always the same

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13
Q

What is the atomic number?

A

The number of protons (and therefore the number of electrons)

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14
Q

What is the mass number?

A

The total number of protons and neutrons

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15
Q

What do some substances give out from their nuclei all the time?

A

Radiation

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16
Q

What are substances that give out radiation from their nuclei?

A

Radioactive

17
Q

What does background radiation come from?

A

Natural sources mainly: cosmic rays, rocks and soil, living things. However it can also come from artificial sources such as nuclear weapons and accidents

18
Q

How many protons and neutrons does an alpha particle have?

A

2 protons and 2 neutrons

19
Q

What is a beta particle?

A

An electron

20
Q

What is gamma radiation?

A

A type of electromagnetic radiation

21
Q

What happens in alpha decay?

A

The atomic mass number decreases by 4, and the atomic number decreases by 2

22
Q

What is an example of an equation for alpha decay?

A

219 215 4
Rn ====> Po + α

86 84 2

23
Q

What happens in beta decay?

A

The atomic mass number stays the same, but the atomic number increases by 1

24
Q

What is an example of an equation for beta decay?

A

14 14 0
C ====> N + β
6 7 -1

25
Q

What can alpha radiation be stopped / absorbed by?

A

A sheet of paper or a human hand

26
Q

What can beta radiation be stopped / absorbed by?

A

A thin sheet of aluminium

27
Q

What can gamma be stopped / absorbed by?

A

Lead or concrete

28
Q

How far can alpha radiation travel in the air?

A

A few centimetres

29
Q

How far can beta radiation travel in the air?

A

Tens of centimentres

30
Q

How far can gamma radiation travel in the air?

A

Very large distances

31
Q

What happens to alpha and beta at electric and magnetic fields?

A

They are deflected

32
Q

Is gamma deflected at electric and magnetic fields?

A

No

33
Q

Why are alpha and beta deflected by electric / magnetic fields when gamma is not?

A

Because alpha carries a positive charge and beta a negative charge, this means they are deflected by the magnetic / electric fields. Whereas gamma is neutral so does not carry a charge and is therefore not deflected

34
Q

What is the half-life of a radioactive isotope?

A

The average time it takes for the number of nuclei of the isotope in a sample to halve. Or the time it takes for the count rate from a sample containing the isotope to fall to half its initial level

35
Q

Why is alpha radiation so dangerous inside the body?

A

Because it is easily absorbed by cells

36
Q

Why is beta and gamma radiation so dangerous outside the body?

A

Because they can penetrate the skin and damage the cells inside

37
Q

Why are beta and gamma radiation less dangerous inside the body?

A

Because they are less likely to be absorbed by the cells, they will most likely just pass through them

38
Q

Why is alpha radiation less dangerous outside the body?

A

Because it is less likely to penetrate the skin and reach the living cells inside the body

Physics: P2 (6 decks)

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