3.7 Particles and Nuclear Structure

what two types of particles is all matter made up of?

quarks and leptons

what are fundamenta particles?

particles that cannot be broken down any further

why is an atom not fundamental?

it contains smaller particles: protons, neutrons and electrons

why are protons and neutrons not fundamental?

they contain quarks

what are the first generation of quarks?

up (u) and down (d) quarks

what are the first generation of leptons?

electron (e) and electron neutrino

what is the charge of an electron?

-1

what is the charge of an electron neutrino?

0

what is the charge of an up quark?

2/3

what is the charge of a down quark?

-1/3

what are antiparticles?

each quark and lepton has its own antiparticle with the same mass but opposite charge

what is the charge of a positron?

+1

what is the charge of an electron antineutrino?

0

what is the charge of an anti-up?

-2/3

what is the charge of an anti-down?

1/3

how do you write the symbol for an anti-particle?

place a bar across the top of the particle symbol

what do particles and their antiparticles do to eachother?

annihilate each other

what happens when a particle and it’s anti-particle annihilate each other?

they disappear and produce two photons which travel in opposite directions

what type of particle is a hadron?

composite

what is a composite particle?

a particle that is not fundamental eg made up of quarks

what are the three types of hadrons?

• baryons

• antibaryons

• mesons

what are baryons made up of?

three quarks

what is the structure of a proton?

uud

what is the structure of a neutron?

udd

what is the structure of a delta plus plus?

uuu

what is the structure of a delta minus?

ddd

list some baryons

• protons

• neutrons

• delta

what are antibaryons made up of?

3 antiquarks

what are mesons made up of?

quark-antiquark pairs

give an example of a meson

• pions

what are the four ways in which particles can interact?

• gravitational

• weak

• strong

• electromagnetic

what is the force of attraction between all matter with mass?

the gravitational interaction

how far does the gravitational force extend?

to an infinite distance, but decreases in a inverse square relationship

how strong is the gravitational interaction?

very weak

what interaction is experienced by all leptons and quarks?

the weak force

why are baryons also affected by the weak force?

they are composed of quarks

when is the weak interaction not significant?

when strong and electromagnetic forces are present

what else is the weak interaction responsible for?

reactions where neutrinos and quark flavour changes (when a down changes to an up)

what interaction is experienced by all quarks?

the strong force

what is the range of the strong force?

short

what is the force between all charged particles?

electromagnetic force

what is the range of electromagnetic force?

infinite range

why are neutral hadrons affected by the electromagnetic force?

they are composed of quarks

what is the lepton number of a positron?

-1

what is the lepton number of an electron antineutrino?

-1

what is the lepton number of an electron?

1

what is the lepton number of an electron neutrino?

1

what is the baryon number of a baryon?

1

what is the baryon number of an antibaryon?

-1

what is the baryon number of any other particle?

0

what occurs during bet minus decay?

a neutron turns into a proton which then emits an electron and a electron antineutrino

what three values must you check the conservation of?

• charge

• lepton number

• baryon number