Particles and Radiation

Question 1

Define the A-Z nuclide notation

Answer 1

A = nucleon number (sum of p + n)

Z = atomic (proton) number

Question 2

State the charge and mass of a proton.

Answer 2

Charge = 1.60e-19

Mass = 1.67e-27

Question 3

How do you calculate the specific charge and what is its unit?

Answer 3

• specific charge = charge/mass
• unit = Ckg^-1

Note : charge = Z x 1.60e-19
mass = A x 1.67e-27

Question 4

How many electrons are there in a neutral atom?

Answer 4

The number of electrons = the number of protons.

Question 5

State the charge and mass of a neutron

Answer 5

Charge = o
Mass = 1.67e-27

Question 6

State the charge and mass of an electron.

Answer 6

Charge = -1.60e-19
Mass = 9.11e-31

Question 7

What is an isotope?

Answer 7

A version of an atom with the same number of protons but different numbers of neutrons.

Question 8

What characteristic of the atom does changing the number of neutrons affect?

Answer 8

The stability of the nucleus.

Question 9

What is ionisation?

Answer 9

The removal (or addition) of electrons from (to) an atom or molecule.

Question 10

How is isotopic data used?

Answer 10

Used to find the percentage of radioactive carbon-14 left in an object (organic matter).

So the approximate age can be calculated.

Question 11

What is the attractive force responsible for holding the nucleus together?

Answer 11

The strong nuclear force.

Question 12

What is the range of the strong nuclear force?

Answer 12

• 0.5-3.0 femtometres
• works equally between all nucleons
• at separations smaller than 0.5fm, the force is repulsive so nucleus doesn’t crush to a point
• falls rapidly towards zero after 3fm.

Question 13

What kind of nuclei is alpha decay likely to happen and how does the nucleon and atomic numbers change?

Answer 13

• very large nuclei
• nucleon number decreases by 4
• atomic number decreases by 2

Question 14

Why is the neutrino present in beta minus decays?

Answer 14

• Hypothesised as a neutral, almost zero mass

- carries away some energy and momentum (conservation of energy)

Question 15

What happens to the nucleon and proton number in beta minus decay?

Answer 15

• the nucleon number stays the same
• the proton number increases by 1
• a beta minus particle and antineutrino are also emitted

Question 16

When does gamma radiation take place?

Answer 16

• gamma radiation is electromagnetic radiation emitted by an unstable nucleus
• it is emitted by a nucleus with too much energy, following alpha or beta emission

Question 17

What end of electromagnetic radiation has the greatest frequency and wavelength?

Answer 17

• highest wavelength = rich men (radio waves -> microwaves)

- frequency = gambling (gamma rays)

Question 18

What do electromagnetic radiation exist as?

Answer 18

Photons of energy = hf

h = 6.63e-34
f = c/lambda

Question 19

What do electromagnetic waves consist of?

Answer 19

• an electric wave and a magnetic wave which
  • vibrate perpendicular to each other and the direction they’re travelling• travel in phase with each other.

Question 20

What similarities do particles and it’s corresponding antiparticles share? (Name one difference)

Answer 20

• same mass
• same rest energy
• opposite charge

Question 21

What happens in annihilation?

Answer 21

• a particle and its corresponding antiparticle collide and their mass is converted into radiation energy
• two gamma ray photons
• Emin = hfmin

Question 22

What happens in pair production?

Answer 22

• a photon creates a particle and a corresponding antiparticle and vanishes in the process
• Emin = 2rest energy

Question 23

State the electron capture equation.

Answer 23

p + e- -> n + v

Question 24

State the 3 fundamental forces, their gauge bosons and the particles affected.

Answer 24

1. Electromagnetic, virtual photon, charged particles only
2. Weak nuclear force, W+ or W- boson, all types
3. Strong nuclear force, pions, hadrons only

Question 25

State the beta plus and beta minus equations

Answer 25

beta minus = n -> p + e- + antineutrino

beta plus = p-> n + e+ + neutrino

Question 26

What is the role of exchange particles?

Answer 26

Exchange particles transfer

1) energy
2) momentum
3) force

Question 27

What occurs in electron capture?

Answer 27

An orbital electron interacts with a proton in the nucleus via the weak interaction.