Module 6: Radiation And Health

Question 1

Bound state

Answer 1

An orbital in which the electron is trapped in the electrical potential produced by the nucleus

Question 2

What does energy quantisation mean?

Answer 2

The total energy of an electron in a bound state can only take on certain values

Question 3

Ground state

Answer 3

The energy level of an electron with the lowest energy

Electrons will almost always be in their ground state

Question 4

Excited state

Answer 4

A state with energy higher than the ground state

Question 5

p = E/c gives the momentum of what?

Answer 5

A photon

Question 6

Ionisation energy

Answer 6

The amount of energy required to free an electron from an atom

Question 7

What is ionisation energy determined by? (2)

Answer 7

Nature of the atom

Orbital from which electron originates

Question 8

Define the electron volt eV

Answer 8

The electrostatic potential energy gained by an electron when it is moved up a potential difference of one volt

Question 9

r = n^2 aB

What is this formula used for?

Answer 9

To give the allowed radii for electronic orbitals

Question 10

What is the ground state, E0, of the hydrogen atom?

Answer 10

13.6 eV

Question 11

What does En = -(Z^2)/n^2 E0 represent?

Is this positive or negative? Why?

Answer 11

The energy of the allowed electronic orbitals

Negative

It takes energy to get the electron unbound

Question 12

Hydrogen-like atoms

Answer 12

Atoms with one electron (H, He+, Li2+)

Question 13

In the energy difference between two levels equation, what do n1 and n2 represent?

Answer 13

n1= lower energy level
n2= higher energy level

Question 14

Chemical properties depend entirely on _

Answer 14

Z atomic number

Question 15

Nucleon

Answer 15

Nuclear constituent (neutron or proton)

Question 16

Atomic mass of carbon in amu

Answer 16

12 amu

Question 17

Strong nuclear force

Answer 17

Short range attractive force

Bond protons to protons, neutrons to neutrons, and protons to neutrons

Due to the force between quarks

Question 18

When is the strong nuclear force overcome? What by?

Answer 18

When the size of the nucleus gets too large

Electrostatic force

Question 19

What is the difference in mass between the atom and its constituent parts called?

Answer 19

Mass defect

Question 20

Binding energy

Answer 20

Energy we would need to break the atom into its constituent parts

Question 21

Which element has the largest amount of energy per nucleon?

Answer 21

Fe iron

Question 22

Three types of nuclear reaction

Answer 22

Nuclear decay
Nuclear fusion
Nuclear fission

Question 23

In fusion and fission, the products are ___ stable than the reactants

Why?

Answer 23

More

Energy is released

Question 24

Nuclear fusion occurs for elements with an atomic number of ____

Answer 24

Smaller than 56

Question 25

Nuclear fission occurs for elements with an atomic number of _____

Answer 25

Greater than 56

Question 26

When you break an atom up into its constituent parts, the binding energy converts to ___

Answer 26

Mass

Question 27

Process by which an unstable nucleus transforms into a more stable nucleus

Answer 27

Nuclear decay

Question 28

Three types of radiation

Answer 28

Alpha (He nucleus) Beta (positron or electron) Gamma rays (photons)

Question 29

Which type of radiation particle is the largest? Is it also the most harmful?

Answer 29

Alpha Most can’t get through the skin

Question 30

Order radiation types by their speed

Answer 30

Gamma (light) Beta (90% speed of light) Alpha (10% speed of light)

Question 31

How does the atomic and mass number of an atom change when it emits an alpha particle?

Answer 31

Mass number -4 | Atomic number -2

Question 32

How does the atomic and mass number of an atom change when it emits a beta particle?

Answer 32

Mass number doesn’t change (electron/ positron mass is extremely small) Atomic number + or -1

Question 33

What is emitted in beta- decay?

Answer 33

Electron and anti neutrino

Question 34

What is emitted in beta+ decay?

Answer 34

Positron and neutrino

Question 35

Which end of the electromagnetic spectrum do gamma rays occupy?

Answer 35

High end | Very high frequency light

Question 36

How do the atomic and mass numbers of an atom change when it emits gamma rays?

Answer 36

No change (photons have no charge) Only state of excitation changes

Question 37

What does lambda symbolise in radiation formulae?

Answer 37

Decay constant

Question 38

The larger the decay constant, the ______ the number of radioactive atoms decreases

Answer 38

Faster

Question 39

What does A symbolise in radiation formulae?

Answer 39

Nuclear activity (rate at which radioactive elements decay)

Question 40

Bq

Answer 40

Becqueral (unit for nuclear activity)

Question 41

Describe Bremmstrahlung radiation

Answer 41

Electrons decelerate and emit energy as photons (X-rays)

Question 42

What is the maximum possible photon energy in an X-ray?

Answer 42

The same as the kinetic energy gained by electrons from the accelerating potential

Question 43

What is Z-eff?

Answer 43

Z effective (Z-1)

Question 44

What makes Coolidge tubes better than Crookes tubes in measuring radiation?

Answer 44

The voltage (penetrating ability) and current (beam intensity) are independent of each other

Question 45

Annihilation

Answer 45

The conversion of mass to energy when a particle and its anti-particles meet (e.g. positron and electron)

Question 46

A higher energy level of the same type of radiation increases what?

Answer 46

Depth/ range of ionisation

Question 47

What do collisions involving beta particles result in for those beta particles? Why?

Answer 47

Large changes in their direction and velocity They are very small and light

Question 48

Three ways X-rays and gamma rays can interact with matter

Answer 48

Photoelectric effect Compton scattering Pair production

Question 49

Describe the photoelectric effect

Answer 49

Electron absorbs a photon, which gives it enough energy to jump out of its orbit A free electron and ion are generated

Question 50

What condition must be met for the photoelectric effect to appear?

Answer 50

The energy of the photon must be larger than the binding energy of the electron

Question 51

What happens if the photoelectric effect is due to X-rays?

Answer 51

X-ray is absorbed and a photoelectron is expelled Electron from outer orbital drops into vacant orbital and another X-ray is emitted

Question 52

Describe the Compton effect

Answer 52

Incoming photon interacts with loosely bound outer electron then leaves with less energy Electron leaves and atom becomes an ion

Question 53

Describe pair production

Answer 53

A photon with very high energy can spontaneously convert into an electron-positron pair (energy—> matter)

Question 54

Free radicals

Answer 54

Molecules which contain unpaired electrons Very reactive Can alter important cellular molecules

Question 55

Deterministic effects of radiation

Answer 55

Early effects Kills cells Reduces an organs function

Question 56

Stochastic effects of radiation

Answer 56

Late effects Doesn’t kill cells- just damages them Imperfect repair= mutation Cause cancer later in life

Question 57

Absorbed dose

Answer 57

Represents the energy imparted by radiation into material

Question 58

D=deltaE/deltam

Answer 58

D is absorbed dose DeltaE is energy lost from beam Deltam is mass of material which absorbs the radiation