Topic 7 Atomic, Nuclear and particle physics

Question 1

What did Rutherford’s experiment achieve?

Answer 1

It proved the existence of the nucleus

Question 2

Why did they use alpha particles in Rutherford’s experiment?

Answer 2

• The mass was large enough to not be deflected by electrons
• It is positively charged to investigate the charge distribution

Question 3

Describe Thompson’s Plum Pudding Model

Answer 3

Atoms were thought to be a cloud if positive charge with negative charges embedded in it

Question 4

Isotope definition

Answer 4

Isotopes are different nuclei of an element that have different number of neutrons (but same number of protons)

Question 5

Nucleon definition

Answer 5

A nucleon is any particle in the nucleus (ie. proton or neutron)

Question 6

What is a strong nuclear force

Answer 6

Protons and neutrons are held together by a strong nuclear force which:
- is balanced by repulsion between protons which acts at a long range (Coulomb interaction)
- Acts at a short range ie. protons and neutrons must be adjacent

Question 7

Describe band of stability

Answer 7

As the atom gets larger, it requires more neutrons, if not, the nucleus decays to form more stable smaller nuclei (radioactivity)

Question 8

What is a alpha particle

Answer 8

Helium nucleus

Question 9

What is beta -ve decay

Answer 9

An electron emitted from the nucleus (neutron => proton)

Question 10

What is beta +ve decay

Answer 10

Emits a positive electron or positron (proton => neutron)

Question 11

what is an alpha particle’s range in air

Answer 11

5cm

Question 12

what is a beta particle’s range in air

Answer 12

30cm

Question 13

what is a photon particle’s range in air

Answer 13

can be hundreds of meters

Question 14

what stops alpha particle’s radiation

Answer 14

a piece of paper

Question 15

what stops beta particle’s radiation

Answer 15

1mm of aluminium

Question 16

what stops photon particle’s radiation

Answer 16

10cm of lead

Question 17

What is ionisation

Answer 17

The removal of an electron from an atom or molecule

Question 18

What accompanies beta -ve decay

Answer 18

Antineutrino

Question 19

What accompanies beta +ve decay

Answer 19

Neutrinos

Question 20

Half-life definition

Answer 20

The time taken for half of the nuclei in a sample to decay. It is spontaneous and random

Question 21

What are the effects of radiation

Answer 21

• cells are damaged but repair themselves correctly
• cells are damaged but repair themselves incorrectly
• cells die

Question 22

Transmutation definition

Answer 22

Nuclei change from one element to another by the addition of nucleons. Can occur naturally or spontaneously

Question 23

Nuclear fission

Answer 23

Large nuclei are broken down into smaller nuclei by being bombarded with neutrons or alpha particles. This is how energy is produced in nuclear power plants.

Question 24

Nuclear fusion

Answer 24

Small nuclei are combined to form larger nuclei if temperature and pressures are high enough to give them the energy to overcome electrostatic repulsion between them.

Question 25

unified atomic mass unit (u)

Answer 25

it is equivalent to the mass of 1/12 of a 12C atom

Question 26

Mass defect

Answer 26

the difference in mass between individual nucleons and their total mass when bound

Question 27

binding energy

Answer 27

the amount of energy required to break apart a nucleus into seperate nucleons

Question 28

binding energy per nucleon (bepn)=

Answer 28

total binding energy / number of nucleons

Question 29

the greater the binding energy per nucleon, _______________

Answer 29

the more stable the nucleus

Question 30

what is the most stable atomic nucleus

Answer 30

56Fe

Question 31

energy released =

Answer 31

total binding energy of PRODUCTS –total binding energy of REACTANTS

Question 32

what happens when a particle and an anti-particle combine?

Answer 32

they annihilate each other and their total mass is converted to energy in the form of a pair of photons

Question 33

what family are leptons a part of

Answer 33

electron

Question 34

name all the quarks

Answer 34

up down strange charm top bottom

Question 35

what are hadrons

Answer 35

groups of quarks

Question 36

meson definition

Answer 36

formed from quark-antiquark pairs

Question 37

baryon definition

Answer 37

formed from 3 quark or 3 antiquarks

Question 38

why can quarks not exist alone

Answer 38

if two quarks move apart, energy is required. the further they move apart, the more energy must be put in. this energy, however, does not break the forces between the quarks but instead is converted into mass and produces a new quark

Question 39

what baryon number does a anti-quark have

Answer 39

-1/3

Question 40

what quarks does a proton consist of

Answer 40

uud (up up down)

Question 41

what quarks does a neutron consist of

Answer 41

udd (up down down)

Question 42

what is a virtual particle

Answer 42

they cannot be detected during their transfer between particles because detection would mean that it is no longer acting as a mediator between the particles

Question 43

what is the purpose of a gauge boson

Answer 43

they mediate (or transmit) forces between particles; the larger the mass, the shorter the range

Question 44

what hold hadrons together

Answer 44

gluons gluons are in-between

Question 45

what is the purpose of gluons

Answer 45

to hold hadrons together

Question 46

what keep a number of hadrons together

Answer 46

pions (pi mesons) pions are across

Question 47

what do W+ and W- bosons do

Answer 47

they transfer charge between weak interaction

Question 48

what do Z0 bosons do

Answer 48

they transfer momentum and energy

Question 49

what is conserved during any vertex (interaction between particles)

Answer 49

- charge - lepton number - baryon number - mass-energy - momentum * strangeness is only conserved with strong interactions (between quarks)

Question 50

what is the Higgs boson

Answer 50

the reason by which particles acquire mass. particles gain mass by interacting with this boson. due to its high mass a great deal of energy was required to produce the Higgs boson

Question 51

what fundamental force acts on quarks (not leptons)

Answer 51

strong nuclear force

Question 52

what fundamental force acts on leptons and quarks

Answer 52

weak nuclear force

Question 53

what is a beta particle's range in air

Answer 53

30cm

Question 54

how do you convert eV to J

Answer 54

times by 1.6 x 10^ –19

Question 55

how do you convert J to eV

Answer 55

divide by 1.6 x 10^ –19

Question 56

how do you convert MeV to eV

Answer 56

times by 10^6