Radioactivity

Question 1

What is atomic number?

Answer 1

Z/number of protons

Question 2

What is atomic mass?

Answer 2

A/Number of nucleons

Question 3

What is the symbol for neutrons?

Answer 3

n

Question 4

What affects how stable an atom is?

Answer 4

The number of neutrons to protons

Question 5

Why does the atom need neutrons?

Answer 5

Without neutrons, the protons would repel each other

Question 6

What is the force that holds the nucelus together?

Answer 6

Nuclear force

Question 7

With more protons present, would we need more or less neutrons?

Answer 7

More neutrons

Question 8

T/F

The first 20 elements have a 1:3 ratio of neutrons to protons.

Answer 8

False; the first 20 elements have a 1:1 ratio

Question 9

T/F

In nuclei with the atomic number greater than 20, the number of neutrons exceeds the number of protons.

Answer 9

True

Question 10

What is decay?

Answer 10

The release of a particle that could cause damage

Question 11

What is the purpose of radioactivity?

Answer 11

To achieve the ideal balance of neutrons and protons through disintegration

Question 12

Is it possible to control the rate of radioactive breakdown of a nucleide?

Answer 12

No

Question 13

What type of nucleide is created from a parent radionuclide disintegrating?

Answer 13

Daughter product

Question 14

What is an isotope?

Answer 14

An atom with the same number of protons but a different number of neutrons

Question 15

T/F

A radioisotope can be natural or man-made.

Answer 15

True

Question 16

What element is the last stable element?

Answer 16

83 (bismuth)

Question 17

How many protons at minumum do elements need to have to be conisdered radioactive?

Answer 17

84 protons at minumum

Question 18

T/F

Everything about an atomic number of 83 cannot exist in a stable state, so they will decay.

Answer 18

True

Question 19

What is the neutron to proton ratio for elements with an atomic number of 1-20?

Answer 19

1

Question 20

What is the neutron to proton ratio for elements with an atomic number of 20-40

Answer 20

1.25

Question 21

What is the neutron to proton ratio for elements with an atomic number of 40-83?

Answer 21

1.5

Question 22

T/F

In a nuclear reaction all the protons and neutrons in a nucleus must be accounted for on both sides of the reaction.

Answer 22

True

Question 23

What do each of these letter stand for in the following equation?:
X–> R + Y

Answer 23

X=Reactants
R+Y=Products

Question 24

What are the 3 different types of radioactive decay?

Answer 24

1. Alpha decay
2. Beta decay
3. Gamma decay

Question 25

What does the type of radioactive decay depend on?

Answer 25

How its neutron to proton ratio compares with those elements of a nearby nucli that lie within the belt of stability

Question 26

# T/F Alpha paricle are light.

Answer 26

False; heavy nuclei

Question 27

What is the problem with the nuclei that leads to alpha decay?

Answer 27

The nucleus is too large to balance forces (the atomic mass is too high)

Question 28

What is an alpha particle made up of?

Answer 28

2 protons and 2 neutrons

Question 29

What is an alpha particle identical in mass and number to?

Answer 29

Helium

Question 30

What reaction has occured here?

Answer 30

Alpha decay

Question 31

How does alpha decay solve the issue with unstable elements?

Answer 31

The release of alpha particles decrease atomic mass, solving the issue of heavy unstable elements

Question 32

What direction does the nucleus move towards the belt of stability?

Answer 32

To the left and diagonally towards the belt of stability

Question 33

What is the charge of an alpha particle?

Answer 33

Positive

Question 34

# T/F Alpha particles are very ionizing.

Answer 34

True

Question 35

How far can an alpha particle travel in air and soft tissue?

Answer 35

Air: 1-10 cm Soft tissue: .1mm

Question 36

# T/F Beta- particles are have neutron rich nuclei.

Answer 36

True

Question 37

What is the problem with the elements that result in beta negative decay?

Answer 37

There are too many neutrons (the n:p ratio is too high)

Question 38

# T/F In beta negative decay, the mass will not change

Answer 38

True

Question 39

What is the mass of a beta particle?

Answer 39

0

Question 40

How do you know that alpha decay will take place?

Answer 40

If the atomic number is over 80

Question 41

What is the solution for Beta particle (𝛽-) emission to get back to the nuclear belt of stability?

Answer 41

Decrease the number of neutrons by one, and increase the number of protons by one

Question 42

What is the end product?

Answer 42

137Ba 56

Question 43

Which way does the decay scheme go for beta negative decay?

Answer 43

Down and to the right

Question 44

# T/F A beta negative particle has the same mass and charge as an electron.

Answer 44

True

Question 45

What is the range of penetration for beta negative particles?

Answer 45

3mm in soft tissue

Question 46

# T/F Beta positive particles have proton rich nuclei

Answer 46

True

Question 47

What is the issue with the unstability of beta positive particles?

Answer 47

-Too many protons -n:p too low

Question 48

What is the symbol for beta positive decay?

Answer 48

Question 49

What is the solution for unstable beta positive particles?

Answer 49

-Reduce atomic number or increase the number of neutrons

Question 50

What is the end product?

Answer 50

15N 7

Question 51

What happends to beta positive particles after they decay?

Answer 51

They combine with negative electrons and disappear in annihalation radiation

Question 52

Write out the radioactive decay reaction for:

Answer 52

238U(92)--->4a(2)=234Th(90)

Question 53

1. Is it stable or radioactive 2. What type of emmission would it give off? 3. Write out the nuclear reaction formula

Answer 53

1. Radioactive 2. Beta negative 3. 0B(-1)=**90Ga(31)**

Question 54

1. Is it stable or radioactive 2. What type of emmission would it give off? 3. Write out the nuclear reaction formula

Answer 54

1. Radioactive 2. Beta positive 3. 0B(+1)=100Pr(59)

Question 55

1. Is it stable or radioactive 2. What type of emmission would it give off? 3. Write out the nuclear reaction formula

Answer 55

1. Stable 2. None 3. None

Question 56

If the n:z ratio is too high, what is likely to occur?

Answer 56

Neutrons are converted to protons via beta decay

Question 57

If the n:z ratio is too low, what is likely to occur?

Answer 57

Protons are converted to neutrons via positiron emission

Question 58

If amu is too high what is likely to occur?

Answer 58

A change to both nuetrons and protons through alpha decay

Question 59

# What process is this describing A nuclear processes in which a nucleus with excess E following alpha or beta particle emission, emits E without chaning number of protons or neutrons.

Answer 59

Isomeric Reaction

Question 60

# T/F The exitied nuclear state following the emission of a beta or alpha particle may be nearly stable.

Answer 60

True

Question 61

# T/F Gamma emission decay processes often leave the daughter nucleus in an excited state.

Answer 61

True

Question 62

# T/F No numbers change in gamma decay.

Answer 62

True

Question 63

What does metastable mean?

Answer 63

Too much energy

Question 64

What is the symbol for gamma radiation?

Answer 64

0y 0

Question 65

# T/F Gamma radiation emission affects the n:z ratio

Answer 65

False; Does not affect the n:z ratio.

Question 66

What is the charge and mass of a gamma particle?

Answer 66

Zero

Question 67

How much soft tissue can a gamma particle penetrate?

Answer 67

30cm in soft tissue

Question 68

What radionuclide is used in radiotherapy?

Answer 68

60CO 27

Question 69

What is absorbed dose?

Answer 69

Absorbed dose is a measure of the energy absorbed per unit mass of tissue

Question 70

What is LET

Answer 70

Average (radiation) energy deposited per unit path length along the track of an ionizing particle

Question 71

What are the units for LET?

Answer 71

keV/μm

Question 72

What does LET depend on?

Answer 72

1. the nature of the radiation 2. material traversed

Question 73

# T/F A high LET will attenuate the beam/particle more quickly

Answer 73

True

Question 74

What are 3 examples of high LET radiation?

Answer 74

1. α-particles 2. protons 3. neutrons

Question 75

# Is this high or low LET? 3 – 200 keV/µm

Answer 75

High LET

Question 76

What are 4 examples of low LET radiaton?

Answer 76

1. Electrons 2. positrons 3. gamma rays 4. x-rays

Question 77

# Is this high or low LET radiation? 0.2 – 3 keV/µm

Answer 77

Low LET radiation

Question 78

What is the radioactive half life? What is it denoted by?

Answer 78

-Time that is required for one half of the sample to decay -T1/2

Question 79

**If you start off with 50g of Cs, which has a HL of 14 years, how much Cs will be present 42 years later?**

Answer 79

6.25 gm | Ask

Question 80

What is radioactive activty? What is it denoted as?

Answer 80

-Number of radioactive decays per second -A

Question 81

What is the SI Unit for radioactivity?

Answer 81

Becquerel (Bq)

Question 82

# T/F Bq is defined as an activity of one transformation/decay per second

Answer 82

True

Question 83

# T/F 1 Bq = 10/s

Answer 83

False; 1 Bq = 1/s

Question 84

What does radoactive activity depend on?

Answer 84

1. Amount of the substance 2. Half life

Question 85

Will a higher mass of a radioactive substance produce more or less activity?

Answer 85

More activity

Question 86

What is the relationship between mass and activity?

Answer 86

Directly proportional

Question 87

Will a long half life have more or less activity?

Answer 87

Less activity

Question 88

What is the relationship between half life and activity?

Answer 88

Indirectly proportional

Question 89

What is the Decay constant (⋋)?

Answer 89

The number of atoms of the radionuclide breaking down per unit time (per second)

Question 90

If the total number of atoms in a radionuclide is 5000000, and the number of atoms breaking down per second is 50000, then what is the decay constant (⋋)?

Answer 90

⋋ = 50000/5000000 = 0.01 = 10^-2/s

Question 91

# T/F Half life and decay rate are constant.

Answer 91

True

Question 92

What is the relationship between half life and decay rate?

Answer 92

They are inversely proportional to eachother. ## Footnote The shorter the half life, the faster/larger the decay

Question 93

What are the two uses for radioactive activity in medical imaging?

Answer 93

1. Theraputic reasons 2. Diagnostic reasons

Question 94

What are the 3 studies done with radioactive activity for diagnostic purposes?

Answer 94

1. Physiological studies 2. Blood volume studies 3. Imaging studies

Question 95

What are blood volume studies done with radioactive materials?

Answer 95

Total volume of blood can be estimated by measuring its diluting effect on a known amount of radionuclide

Question 96

# Pictures for understanding

Answer 96