Nuclei and Particles

Question 1

Atomic Mass (A), Atomic no (Z)

Answer 1

A=protons+Neutrons, Z=Protons

Question 2

Isotope

Answer 2

Same element, different atomic mass. different no of neutrons

Question 3

isotope notation

Answer 3

2 numbers in front of element symbol (upper for atomic mass, lower for atomic no)

Question 4

Nucleon

Answer 4

collective name for protons and neutrons

Question 5

Ion

Answer 5

one or more electrons added or removed from neutral atom….electrically charged ion formed

Question 6

speed of light

Answer 6

3 x 10^8 ms-1

Question 7

energy and mass interchangeable due to e=mc^2

Answer 7

so can refer to subatomic particles by their energy not mass (mass energy). MeV mega electronvolts). Or expressed as E/c^2 in keV (kilo electron volts (thousand electron volts)

Question 8

Proton mass

Answer 8

proton almost 2000 times more massive than electron

Question 9

Antimatter

Answer 9

Same mass as matter counterparts, but attributes have opposite sign (eg electron charge)

Question 10

positron

Answer 10

Antimatter counterpart of electron

Question 11

antiproton

Answer 11

Antimatter counterpart of proton

Question 12

Matter - antimatter annihilation

Answer 12

Collision between matter and antimatter. particle + antiparticle…photons. Large amount of energy

Question 13

Pair production

Answer 13

photons…Particle + antiparticle

Question 14

Energy time uncertainty principle.

Answer 14

Time a particle can exist with “borrowed” energy. Rearranged to delta t = h/(4pi x delta E) to find time…orig eq: delta E x delta t is approx = to h/4pi

Question 15

Quantum jump

Answer 15

Occur between energy levels. For nuclei, gamma ray photons emitted, hundreds of thousands of times more energy than with visible photons. 1MeV(mega electron volt) compared to 2 or 3 eV

Question 16

Mass defect, binding energy

Answer 16

Amount by which the nucleus is less massive than its constituent parts. Binding energy also this amount, so also the same amount of energy need to break apart the nucleus

Question 17

Alpha decay and particle

Answer 17

Emitted during decay,same as helium nucleus, 2 protons 2 neutrons

Question 18

Binding energy of alpha particle

Answer 18

28.3 meV

Question 19

Beta decay

Answer 19

Transformations between neutrons and protons at the heart of it. Beta - decay, beta + decay, electron capture all types of beta decay

Question 20

conservation in nuclear processes

Answer 20

mass, energy, net charge conserved

Question 21

Beta minus decay

Answer 21

Neutron to proton, electron and electron antineutrino (zero charge) created. Extra proton, 1 less neutron so atomic mass same, atomic no +1.

Question 22

Beta plus decay

Answer 22

Proton to neutron, so atomic no -1. Positron (+ as antielectron) and electron neutrino (zero charge) created

Question 23

Electron capture

Answer 23

Nucleus captures an electron, proton interacts with electron forming a neutron, emitting electron neutrino. Atomic no decreases by 1

Question 24

Gamma decay

Answer 24

Nucleus in excited state (from decay), quantum jump to lower energy state, photon emission. Similar process to atoms but gamma ray photon about a million times larger

Question 25

Half life

Answer 25

p=(1/2)^n p_0 n=no of half lives elapsed, p_0 is original amount of atoms (1/2)^n fraction remaining after n no of half lives. D/P = 2^n -1 to work out no of half lives elapsed (d, daughter, p parent)

Question 26

Nuclear fission

Answer 26

Relatively massive nucleus splits

Question 27

Nuclear fusion

Answer 27

2 or more low mass nuclei join together to form a heavier nucleus

Question 28

Neutrino

Answer 28

As neutral charge, not affected by electromagnetic forces which act on electrons, so can pass through greater distances in matter

Question 29

Leptons

Answer 29

Muon, Tauon, Lepton. muon neutrino, Tauon neutrino, electron neutrino. There is an antilepton antimatter particle for each, with opposite charge (if charges as in electron ,muon and tauon)

Question 30

Quarks

Answer 30

Combine to form hadrons (protons and neutrons are hadrons). Up, down, charm, strange, top, bottom are the 6 flavours of quarks.u,c,t pos charge 2/3e, d,s,b neg -1/3e charge. Antiquark for each. up and down make up protons and neutrons

Question 31

Hadrons

Answer 31

Made up of Quarks and Antiquarks. 3 quarks = baryon, 3 antiquarks = antibaryon, 1 quark, 1 antiquark = meson. Protons and neutrons are baryons.

Question 32

Particle generations

Answer 32

12 fundamental particles (6 leptons, 6 quarks plus their antiparticles). Almost everything made up of first generation leptons and quarks (electrons, up and down quarks, electron neutrinos being created in decay). 2nd gen: Muon, muon neutrino leptons, charm and strange quarks. 3rd gen: Tauon, tauon neutrino, top and bottom quarks

Question 33

High energy particle reaction rules

Answer 33

Quantum indeterminacy as to what is produced…but 3 rules. Energy conserved, electric charge conserved, no of quarks - no of antiquarks conserved

Question 34

Quarks do not come out in collision

Answer 34

Their KE is transformed into mass of new hadrons

Question 35

Strong interaction

Answer 35

Mechanism for strong nuclear force, binds quarks together, residual strong interaction binds nucleus in nuclei

Question 36

Gluons

Answer 36

Elementary particle, acts as exchange particle for strong force between quarks. Holds quarks together, sometime emitted by quarks after collision. Zero electric charge. Carry a combination of colour and anticolour charge

Question 37

Quantum Chromodynamics (QCD)

Answer 37

Quantum theory of the strong interactions between quarks and gluons. Colour charge. Red, Green, Blue, each + or -. Opposites are antired (cyan), Antigreen (magenta), Antiblue (yellow). Carried by gluons. Leptons and photons have no colour charge. Colour charge conserved in strong interactions. Baryons have quarks 1 of each colour (neutral charge as red + green + blue = white). Antibaryons have neutral charge as 1 of each anticolour. Mesons 1 colour 1 anticolour so neutral.

Question 38

Only particles with net colour charge of zero can exist in an independant state.

Answer 38

So gluons can’t or quarks on their own

Question 39

Neutron and Proton quark composition

Answer 39

neutron udd, proton uud

Question 40

Beta decay at quark level

Answer 40

Quark conversion at heart of it all, as down quark converts to up quark (neutron to proton)

Question 41

Quanta involved in electromagnetic, strong, weak interactions

Answer 41

electromagnetic - photons, strong - gluons, weak - W and Z bosons

Question 42

Weak interaction

Answer 42

All 3 types of beta decay are weak interactions. W and Z bosons created (they have large masses so need more energy in the system to create). If easier to create, decay would be much quicker and we wouldnt exist without the W boson! (neutrons would have decayed very quickly after the big bang)

Question 43

SUMMARY

Answer 43

Leptons, quarks and hadrons:
There are six flavours of lepton, the lightest of which are the electron and electron neutrino; there are six flavours of quark, the lightest of which are the up and down quarks.
All leptons and quarks have corresponding antiparticles with the same mass but opposite electric charge and colour charge (in the case of quarks).
Combinations of three quarks are called baryons; combinations of three antiquarks are called antibaryons; combinations of a quark and an antiquark are called mesons.
As examples, a proton has the quark composition ‘uud’; a neutron has the quark composition ‘udd’; pions are mesons composed of up and down quarks and antiquarks.
Strong and weak interactions:
The strong interaction binds quarks together inside nucleons, and binds nucleons together inside nuclei; all strong interactions involve gluons.
Quarks and gluons each carry a colour charge; baryons, antibaryons and mesons are all colour-neutral.
In strong interactions: energy, electric charge, colour charge and the number of quarks minus the number of antiquarks are all conserved.
The weak interaction allows leptons and quarks to change flavour; all weak interactions, such as beta-decay, involve W or Z bosons.
In weak interactions, energy, electric charge, the number of quarks minus the number of antiquarks, and the number of leptons minus the number of antileptons are all conserved.