5 Nuclear physics

Question 1

Atom

Answer 1

The smallest unit of an element, made from neutrons, protons and electrons.

Question 2

Summary of the constituent parts of an atom

Answer 2

proton p 1 +1
neutron n 1 0
electron e ​​0(12000) −1

Question 3

Nuclide

Answer 3

An atom or nucleus is characterised by a specific number of protons and neutrons.

Question 4

Nuclide notation

Answer 4

A notation using symbols for elements along with the atomic number and nucleon number to describe the composition of an element’s nucleus

Question 5

X

Answer 5

is the symbol for an element.

Question 6

Z (SMALLER NUMBER)

Answer 6

is the proton number but is also called the atomic number. This is the number of protons found in the nucleus. Since atoms are neutral, this is also the number of electrons orbiting the nucleus.

Question 7

A (LARGER NUMBER)

Answer 7

is the nucleon number (also known as mass number). This is the total number of protons and neutrons that are found in the nucleus.

Question 8

Proton number

Answer 8

The number of protons in a nucleus.

Question 9

Atomic number

Answer 9

The number of protons in a nucleus.

Question 10

Mass number

Answer 10

The total number of protons and neutrons in the nucleus, also the total relative mass of the nucleus.

Question 11

Radioactivity

Answer 11

Atoms that are radioactive have unstable nuclei that spontaneously break down. Usually, leads onwards but an exception of technetium.

Question 12

Reasons for instability of an atom

Answer 12

Too many neutrons
Too few neutrons
Too much energy

Question 13

Types of radiation

Answer 13

Alpha
Beta
Gamma

Question 14

Alpha ( α ) Radiation

Answer 14

The nucleus of a helium atom( 2 protons and 2 neutrons)
CHARGE: +3.2x10^-19 / 2
Travel at 10% speed of light
Can only travel 10cm in the air before ionising to helium gas
Blocked by paper
Formula:
X,A,Z –> Y,A-4,Z-2 + α 4,2

Question 15

Beta radiation β

Answer 15

Beta particles(β) are high-speed electrons
When a neutron spontaneously decays into a proton, it also emits beta particles from the nucleus
CHARGE: -1.6x10^-18 / -1
Travel 2.9x10^8 m/s
Can travel through paper but is blocked by thin aluminium
Formula:
X,A,Z–> Y,A,Z+1 + e,0,-1

Question 16

Gamma radiation γ

Answer 16

High-energy electromagnetic waves with a very small wavelength Gamma rays have no mass or charge and are represented by γ
Lowest ionising ability
Highest penetrative ability, block by several centimetres of lead
Formula:
X,A,Z–> Y,A,Z + γ,0,0

Question 17

Penetration and ionising abilities of different radiation

Answer 17

Radiation Ionising effect Penetrating ability
alpha (α) particles strong weak
beta (β) particles mild mild
gamma (γ) emissions weak high

Question 18

Radiation deflection in an electric field

Answer 18

Radiation is deflected within an electric field. Opposite charges attract, so negative Beta particles move towards the positive side.
Positive Alpha particles are attracted to the negative side.
Gamma rays are unaffected since they have no charge
(This only occurs when they travel perpendicular to the field)

Question 19

Radiation deflection in a Magnetic field

Answer 19

Dot: Magnetic field coming out of the page
Dot: Alpha particles go left, Beta particles go right and Gamma is unaffected
Cross: Magnetic field going into the page
Cross: Alpha particles go right, Beta particles go left and Gamma is unaffected

Question 20

Right hang slap rule

Answer 20

Thinger tips are the direction of the magnetic field
Force on positive charge is the palm/negative charge is knuckles
Thumb of direction of moving charge

Question 21

Background radiation

Answer 21

There is a natural supply of background radiation all around us (Radiation we experience without measuring a specific object)
This can be found from: Food, Building materials and rocks, Radon gas, Cosmic rays, medical procedures
Formula: Radiation measured-background = Object radiation

Question 22

Radon gas

Answer 22

Radon gas is naturally found in the atmosphere due to uranium decay in the ground

Question 23

Cosmic rays

Answer 23

Cosmic ray is a generic term used to describe particles and waves that come from space.
The high energy radiation comes from outside of our solar system with its exact origins unknown

Question 24

Half-life

Answer 24

The time taken for half of the nucleus in a sample of radioactive material, to decay.
All decay is random and spontaneous. You can not predict when it will decay
A half-life measurement is a probability of when half a sample has decayed
On a graph, the y-axis could be the Nuclei number, count rate, mass
without graph: Number of nuclei remaining= Original amount÷ 2^n(n=the number of half-lives that have happened)

Question 25

Uses for half lives

Answer 25

Smoke detector
Thickness measurements and Quality control
Fault detection
Food irradiation
Cancer treatment
Organ function and blood flow testing

Question 26

The effects of ionising radiation

Answer 26

Radioactive materials are dangerous because ionising radiation can damage cells. In humans, exposure to radiation can result in cancer, radiation burns, mutations, and ultimately death.

Question 27

Rutherfords Gold foil

Answer 27

1. The majority of the alpha particles pass through the gold sheet undeflected and are detected on the far side. The majority of the atom is empty (nucleus is small)
2. A small number of alpha particles are deflected as they pass through the gold sheet. There must be a concentrated positive charge (nucleus)
3. A very small number of alpha particles are deflected through very large angles or return back the way they came. The nucleus is most of the mass of the atom and is dense and it hits it straight on.

Question 28

Exposure to radiation may cause the following

Answer 28

Cell death
Genetic mutation
Cancer

Question 29

Contamination

Answer 29

The unwanted presence of materials containing radioactive atoms on other materials

Question 30

Irradiation

Answer 30

Irradiation is the process of exposing an object to nuclear radiation

Question 31

How can Alpha radiation be stored

Answer 31

Alpha can be stored in a thin package
However, protective clothing must still be worn when handling sources of alpha particles as they are very dangerous if they get inside the body

Question 32

How can Beta radiation be stored

Answer 32

Beta must be stored in a lead or similarly dense metal container

Question 33

How can Gamma radiation be stored

Answer 33

Only stopped by thick lead or concrete, so radioactive waste emitting gamma radiation is typically buried deep underground

Question 34

Time exposed to radiation to be safe

Answer 34

Less time spent near source - less radiation recieved

Question 35

Distance to be safe from radiation

Answer 35

Greater distance from the source - less radiation received

Question 36

Shielding to be safe from radiation

Answer 36

Behind shielding from the source - less radiation received

Question 37

Nuclear Fission

Answer 37

The splitting of large nuclei into smaller nuclei, releasing energy in the process
n,1,0 + U,235,92 –> Ba,144,56 + Kr,89,36 + n,3,0

Question 38

Nuclear Fusion

Answer 38

The joining of smaller nuclei into larger nuclei, releasing energy in the process
H,2,1 + H,3,1 –> He,4,2 + n,1,0

Question 39

Energy

Answer 39

E=mc2
Speed of Light= 3x108
Reaxtants–>Products–>Mass lost x c*2= energy released
The products have slightly Less mass than the reactants

Question 40

what is the source of the sun’s energy

Answer 40

Nuclear fusion in the sun’s core