Nuclear and Particle Physics

Question 1

State 3 key facts that Rutherford discovered about the structure of an atom

Answer 1

1. most of the atoms mass is contained within a small volume called the nucleus
2. the nucleus has a postive charge
3. the nuclear diameter is considerably smaller than diameter of atom

Question 2

What is the evidence that Rutherford obtained in order to show that most of the mass is contained within a small volume?

Answer 2

the majority of alpha particles travelled straight through the gold foil and a small no. were deflected while a tiny percentage were scattered right back

Question 3

what is the evidence Rutherford obtained in order to show that the nucleus has a positive charge

Answer 3

alpha particles have a positive charge and so would be deflected/repelled by another positive charge

Question 4

State the size of the nuclear diameter

Answer 4

around 10 ^-14m

Question 5

State the relative size of the diameter of an atom

Answer 5

around 10^-10m

Question 6

proton number

Answer 6

the no. of protons within the nucleus (a.k.a atomic number)

Question 7

nucleon number

Answer 7

the no. of nucleons (protons and neutrons) within the nucleus (a.k.a mass number)

Question 8

isotopes

Answer 8

atoms of the same element with the same number of protons but different numbers of neutrons

Question 9

An atom can represented in the format :

explain what each letter represents

Answer 9

Z= no of protons

no of electrons= Z

no of neutrons = A-Z

Question 10

strong nuclear force

Answer 10

force which acts between nucleons and holds nucleus together against the electrostatic repulsion of protons

Question 11

Explain how the strong force varies with the distance between the centres of adjacent nucleons

Answer 11

strong force provides a repulsive force from a seperation of up to 0.5fm

strong force provides attractive force between distances of 0.5fm to 3fm

beyond a distace of 3fm between necleons the strong force approaches 0

Question 12

State the equation to find the radius of nuclei

Answer 12

R=roA^1/3

where ro is a constant (1.4 fm) and A is the nucleon number

Question 13

Assuiming the nucleus is spherical , state the equations used to find the volume

Answer 13

(4πR³)/3 OR (4πro³A)/3

Question 14

State how you would find the mass of a nucleus

Answer 14

mass of nucleus = mnA

where mn is the mass of a nucleon (1.67x10^27) and A is the nucleon number

Question 15

State the equation used to find the mean density of a nucleus

Answer 15

ρ= (3mn)/ (4πro³)

Question 16

State the corresponding antiparticle for the electron, proton, neutron and neutrino

Answer 16

electron → positron

proton→antiproton

neutron→antineutron

neutrino→antineutrino

Question 17

What are the similarities and differences between a particle and its corresponding antiparticle?

Answer 17

they share the same mass but have opposite charges e.g. both the electron and positron have a mass of 9.11x10^-11kg ,however the electron has a charge of -e whilst the positron has a charge of +e

Question 18

Subatomic particles can be classified into two main groups, what are these groups?

Answer 18

hadrons and leptons

Question 19

Name the particles which are categorised within the hadron group and characteristics of a hadron

Answer 19

protons and neutrons

• theyre composed of quarks which are fundamental particles
• theyre subject to the strong nuclear force

Question 20

Name the particles which are categorised within the lepton group and their characteristics

Answer 20

electrons and neutrinos (as well as their corresponding antiparticles)

• theyre fundamental particles so cannot be broken further down
• all leptons experience the weak nuclear force

Question 21

Name the 3 quarks and their respective antiquarks

Answer 21

up quark → anti-up

down quark→anti-down

strange quark → anti-strange

Question 22

How are antiquarks different to their partner quark?

Answer 22

they have the opposite charge and are composed of antimatter e.g. an up quark has a charge of 2/3e whereas the anti-up quark has a charge of -2/3e

Question 23

State the quark arrangement in each hadron

Answer 23

proton - UUD

neutron-UDD

Question 24

Radioactive decay

Answer 24

its the spontaneous and random decay of an unstable nucleus into a more stable nucleus by the emission of alpha,beta or gamma radiation

Question 25

alpha particle

Answer 25

particle made up of 2 protons and 2 neutrons ejected from the nucleus (helium-nucleus structure)

Question 26

beta particle

Answer 26

fast-moving electron

Question 27

gamma ray

Answer 27

a type of em wave

Question 28

How are alpha particles stopped?

Answer 28

by a few centimetres of air or a sheet of paper

Question 29

How are beta particles stopped?

Answer 29

thin aluminium

Question 30

What blocks gamma rays?

Answer 30

thick lead

(gamma can penetrate through paper and aluminium)