Nuclear Models and Radioactivity

Question 1

What is Mass number

Answer 1

Number of protons plus neutrons

Question 2

What is atomic number

Answer 2

number of protons in a nucleus

Question 3

Consider Co60
27
1. What is the atomic number
2. mass number
3. number of neutrons
4. number of protons
5. number of electrons

Answer 3

1. 27
2. 60
3. 33
4. 27
5. 27

Question 4

What is an isotope

Answer 4

atoms with the same number of protons (atomic number) but a different number of neutrons (mass number)

Question 5

what is an example of isotopes

Answer 5

C12
6
C13
6
C14
6

Question 6

complete following equation and determine the decay
40 A
B K —-20 Ca + +1e + ?
A:
B:

Answer 6

0
? = V
0
A: 40
B: 21

Question 7

write nuclear equation of 144, 60 Nd decaying to Ce by alpha decay

Answer 7

Nd 144, 60—-Ce 140, 58 +a 4,2

Question 8

write equation to show gamma decay of nickel Ni 60, 28

Answer 8

Ni*, 60, 28 —— Ni, 60, 28 +y

Question 9

why does gamma decay accompany another type of radioactive decay?

Answer 9

gamma decay is the release of excess energy. So, if another type of decay left the nucleus with extra energy, gamma decay will eject it from the nucleus.

Question 10

In the decay graph…
1. what type of decay is the top half
2. what is the top right-hand corner
3. what is the middle?

Answer 10

1. beta minus
2. alpha decay
3. beta plus

Question 11

how can someone minimize their exposure to radiation?

Answer 11

-wear protective shielding/ barriers
-limit exposure time
- increase distance away from the radioactive source

Question 12

what is ionizing radiation

Answer 12

radiation that is charged, causes the removal of electrons from atoms in cells.

Question 13

will beta and gamma decay get through a thick piece of steel?

Answer 13

beta wont but gamma will

Question 14

explain the power of each decay

Answer 14

alpha: isn’t too penetrable, absorbed by air, paper or dead skin.
beta: absorbed in 100cm of air or few cm of aluminum
gamma: air has no effect, absorbed in many cm of lead.

Question 15

what is half -life

Answer 15

the time it takes for half of the radioactive substance to decay

Question 16

what is alpha decay

Answer 16

when it occurs, an unstable nucleus ejects an alpha particle - 2 protons and 2 neutrons

Question 17

what is beta plus and minus decay

Answer 17

• a neutron in an unstable nucleus is converted to a proton and an electron and an antineutrino

+ a proton in an unstable nucleus is converted to a neutron and a positron and neutrino. this process cannot occur in isolation as it requires energy

Question 18

what is gamma decay

Answer 18

an unstable nucleus with excess energy ejects gamma radiation

Question 19

what is an induced nuclear reaction

Answer 19

fission and fusion

Question 20

t-99 has a half- life of 6 hours; the initial activity of the sample is 240bq. what is the activity of the sample after one day?

Answer 20

after 24 hours
24/ 6= 4 squared= 16
it will have 4 half lives. inital activty= 240bq
240x 1/16= 15bq
OR 240/2
120/2
60/2
4 half-lives 30/2
= 15

Question 21

what is nuclear fusion

Answer 21

fusion is the joining of two smaller nuclei into one big nucleus and it is not spontaneous

Question 22

what is nuclear fission

Answer 22

fission is when a neutron is absorbed into a big nucleus, it splits into 2 smaller nuclei and releases more than 1 neutron

Question 23

why are alpha particles less penetrating

Answer 23

bigger mass, alpha is slower

Question 24

why are beta particles more penetrating then alpha

Answer 24

smaller, and quicker

Question 25

why are gamma particles very penetrating

Answer 25

they have no mass and very fast (speed of light)

Question 26

types of ionizing radiation

Answer 26

alpha radiation
beta radiation
x-rays
gamma radiation

Question 27

how does ionizing radiation affect the human body and give an example of its effects

Answer 27

ionizing radiation breaks chemical bonds and damage tissue structure.
it can lead to cell mutations causing cancer, kill cells, effect cell function.

Question 28

what is a chain reaction

Answer 28

when a neutron is absorbed by a nucleus causing it to split into 2 more neutrons are released during the fission process. those neutrons then enter more nuclei allowing the, to undergo fission, which releases more neutrons, and it keeps going.

Question 29

explain function of control rods

Answer 29

control rods are raised and lowered to control the amounts of fission reactions as they stop the fission neutrons from moving through the power station

Question 30

explain function of fuel rods

Answer 30

cylinders that contain the uranium fuel pellets for fusion

Question 31

moderator

Answer 31

slows down the reaction neutrons to sustain chain reaction

Question 32

shield

Answer 32

absorbs ionizing radiation to stop it from going into the environment

Question 33

coolant

Answer 33

enters reactor and heated by energy released, then transfers energy to 2nd exchange r coolant in heat exchanger

Question 34

spontaneous fission

Answer 34

occurs without a neutron entering it

Question 35

what is the strong nuclear force

Answer 35

a strong force that is short ranged, is independent of charge and holds the atom together.

Question 36

what is the amount of damage caused by radiation depend on

Answer 36

• the type of radiation
• the amount of radiation
• the energy of the particles
• the material that is irradiated

Question 37

what is required for nuclear fusion to occur

Answer 37

• nuclei need to be close together so the strong force is working, there is large pressure, and the kinetic energies need to be high/ very hot

Question 38

advantages of nuclear fission

Answer 38

energy efficient fuel, alot of fuel, electiricty can be continously produced, no carbon dioxide emmisions.

Question 39

disadvantages of nuclear fission

Answer 39

risk of meltdown or other accident, transporting and storing nuclear fuel, disposal and storage of nuclear waste, cost of building and maintaining a facility is initially high.

Question 40

what is a gamma photon

Answer 40

electromagnetic radiation

Question 41

do nuclear revision sheet