Particles and Nuclides

Question 1

What is the Nucleon Number

Answer 1

The number of protons plus the number of neutrons in the nucleus

Question 2

What is the Atomic/ Proton Number

Answer 2

The number of protons in the nucleus

Question 3

What is Specific Charge

Answer 3

The charge per unit mass of a particle

Question 4

What is the Specific Charge Equation

Answer 4

Specific Charge = Q / m

Specific Charge ( C Kg^-1) = Charge (C) / mass (Kg)

Question 5

What is an Isotope

Answer 5

A nucleus of the same element with the same number of protons but a different number of neutrons

Question 6

What is the Strong Nuclear Forces Role

Answer 6

To keep the nucleus stable against the electrostatic force

Question 7

Describe the Forces within the Nucleus

Answer 7

• From 0 - 0.5 fm (femtometers) the strong nuclear force is strongly repulsive and repels the nucleons to stop them from colliding
• There is also strong electrostatic repulsion between charged particles
• At 1.5fm the strong force becomes strongly attractive and holds the nucleons together by equally balancing the repulsive electrostatic force
• This keeps the nucleons stable
• Beyond 3fm the strong force drops to zero and although the electrostatic force has decreased the strong force does not hold the nucleons in the nucleus so the nucleons separate

Question 8

Describe the Strong Nuclear Force Graph

Answer 8

Question 9

Describe the Electrostatic Force and Strong Nuclear Force Range

Answer 9

• Electrostatic Force - electrostatic force acts between two charged particles has an infinite range, always repulsive
• Strong Nuclear Force - range of 0-3fm ( the diameter of a small nucleus), attractive/repulsive

Question 10

What does the strong nuclear force act on

Answer 10

2 protons, 2 neutrons or a proton and a neutron (anything made of quarks)

Question 11

Why does the strong force need to act between neutrons

Answer 11

Otherwise it would be extremely easy to remove neutrons from the nucleus

Question 12

Why do nuclei decay

Answer 12

To become stable

Question 13

What is Alpha decay

Answer 13

The emission of two protons and two neutrons ( same as a helium nucleus)

Question 14

What happens during Beta minus decay

Answer 14

A neutron turns into a proton and an electron and an anti electron neutrino ( ̅ νe ) are emitted from the nucleus

Question 15

What happens during Beta plus decay

Answer 15

A proton turns into a neutron and a positron and a electron neutrino (ve) are emitted from the nucleus

Question 16

What happens during Gamma Decay

Answer 16

When the nucleons lose energy by giving off electromagnetic radiation

Question 17

Why was the existence of the neutrino hypothesised

Answer 17

To account for the conservation of energy in beta decay

Question 18

What are the ways of detecting nuclear radiation

Answer 18

• Cloud Chamber
• Spark Counter
• Geiger-Muller Tube

Question 19

Explain how a Cloud Chamber works

Answer 19

• Creates an artificial cloud of water or alcohol vapour
• As a charged particle flies through it, a visible trace appears
• The bigger the mass, the bigger the trace
• Alpha go towards the negative, Beta go towards the positive and gamma pass straight through

Question 20

Explain how the Spark Counter works

Answer 20

• A high voltage is set between 2 grids
• As a charged particles flies through it, they produce a spark and sound that can be used to count them
• Only detects highly ionising alpha particles, beta and gamma do not ionise enough in air to be picked up

Question 21

Explain how a Geiger-Muller Tube works

Answer 21

• A voltage is set up between a cathode and the anode
• As a charged particle flies through it, it’s attracted to one of the two creating a current and a counter reads the current to count particles
• Advance over the other methods as it detects alpha and beta very well

Question 22

What are the Energy of Photon Equations

Answer 22

• E = hc / λ
• Energy of a Photon (J) = Planck’s Constant (J s) x Speed (m s -1) / Wavelength (m)
• • E = hf
• Energy (J) = Planck’s Constant (J s) x Frequency (Hz)

Question 23

What is an Electronvolt (eV)

Answer 23

1 electronvolt is the energy required to accelerate the charge of 1 electron through 1 volt

Question 24

What are Antiparticles

Answer 24

Antiparticles have the same mass/ rest-mass energy but opposite charge and other quantum numbers compared to their normal matter counterparts

Question 25

What is Rest-Mass Energy

Answer 25

The amount of energy released by converting all of the mass into energy

Question 26

What is Rest Energy

Answer 26

The minimum amount of energy needed to create a particle

Question 27

What is Annihilation

Answer 27

• When a particle and its corresponding antiparticle collide, as a result their masses are converted into energy
• This energy is released in the form of 2 photons moving in opposite directions in order to conserve momentum

Question 28

What is Pair Production

Answer 28

• When a photon is converted into a particle and antiparticle pair
• This can only occur when the photon has an energy greater than the total rest energy of both particles, any excess energy is converted into kinetic energy of the particles