1. Particles Flashcards
Name the two nucleons that make up an atoms nucleus.
Protons and Neutrons
What is the name of the particle that orbits around the atom in energy shells?
Electrons
Order the 3 particles of an atom in order of highest mass to lowest.
Neutron (1.67(5) x 10^-27), Proton (1.67(3) x 10^-27), Electron (9.11x10^-31)
Which atomic particle has a relative charge of +1.
Proton
Which of the atomic particles is neutrally charged?
Neutron
What is the proton number?
Sometime known as the atomic number, and it is the number of protons in the atoms nucleus. This number determines what element it is.
In a neutral atom, if the atom had 6 protons, how many electrons are there?
6 electrons
What is the nucleon number?
It is the total number of neutrons and protons in the nucleus. Also known as the mass number.
If carbon has a nucleon number of 12 and a proton number of 6, how many neutrons does it have?
12 - 6 = 6 neutrons
Define isotopes.
Atoms with the same number of protons but different numbers of neutrons. This means the atom remains the same element but the mass of the nucleus changes.
What does the number of neutrons in an atom affect in the nucleus?
It’s stability. Unstable nuclei may be radioactive and decay over time to become more stable.
Name a use of radioactive isotopes.
Used to find out how old objects are. All living things contain the same percentage of radioactive carbon-14 taken from the atmosphere. This percentage decreases when the thing dies, due to decay. The age can be approximated for dead organic matter.
Define specific charge.
It is the ratio of a particles charge to its mass.
What is the unit of specific charge?
C/kg
What is the specific charge of a proton?
SC = charge/mass => (1.60 x 10^-19)/(1.67 x 10^-27)
= (9.58 x 10^7)
Name the four fundamental forces.
Strong nuclear, weak nuclear, electromagnetic and gravitational.
What is the strong nuclear force?
An attractive force that opposes the the electromagnetic force, holding nucleons in the nucleus.
What force is stronger, strong nuclear or electromagnetic?
Strong Nuclear.
Does the strong nuclear force have a very large range of a very short range?
Very short range, it can only hold nucleons together that are separated by up to a few femtometres.
What does 1 femtometre equal in metres?
1fm = 1 x 10^-15 m
The strength of the _________ attractive force quickly falls beyond a couple of femtometres.
Strong nuclear
When is the strong nuclear force repulsive?
At very small separation between the nucleons, so that the nucleus doesn’t crush to a point.
Does alpha emission only occur in very large nuclei or very small nuclei?
Very large. This is because the nucleus is so large for the strong force to keep the nucleons together.
Give an example of a element that can emit alpha radiation.
Uranium and radium.
When an alpha particle is emitted…
The proton number decreases by two and the nucleon number decreases by four.
An alpha particle is made up of…
Two protons and two neutrons. (Helium nucleus)
Do alpha particles have a greater range than beta particles.
No, beta has a greater range.
What is the link between alpha particles and a cloud chamber?
The short range of the alpha particles can be seen as tracks in the cloud chamber.
Does beta minus decay happen in neutron-rich nuclei or proton-rich nuclei?
Neutron-rich nuclei. Neutron in the atom is changed into a proton when the beta minus particle is released.
When a beta minus particle is emitted…
The proton number increases by one and the nucleon number remains the same.
What other molecule is emitted during beta minus decay?
Electron Antineutrino.
What is a beta minus particle?
A fast moving electron.
What does the antineutrino conserve in this process?
Energy and momentum.
Name the electromagnetic wave which has the highest frequency.
Gamma rays.
Name the electromagnetic wave that has the highest wavelength.
Radio waves.
Give the equation that links speed (c) , frequency (f) and wavelength (w)
f = c/w
Is electromagnetic waves a transverse or longitudinal wave?
Transverse.
What is the E in the equation: E = hf
The energy of a photon, which is dependent on the frequency.
Define antiparticle.
An antiparticle has the same mass and rest energy as its corresponding particle but has an opposite charge.
What is the antiparticle of an proton?
Antiproton
What is the relative charge of a positron?
+1
Do neutrinos have an antiparticle?
Yes, Anti-neutrino
What is the rest energy of a neutrino?
0
Does a neutron and an anti-neutron have the same mass and rest energy?
Yes.
The rest energy of a particle is just the ‘energy equivalent’ of a particle’s ________
Mass
What is the unit of rest energy?
Electron Volts (or joules)
When energy is converted into mass, you get equal amounts of _______ and ________.
Matter. Antimatter
Energy that gets converted into matter and antimatter is in the form of a _______.
Photon
Pair production can only happen if…
one photon has enough energy that much mass (gamma ray photons only).
What is pair production?
The conversion of one photon into a particle and corresponding antiparticle.
Where does pair production normally take place in order to conserve momentum?
Near the nucleus.
The minimum energy for a photon to undergo pair production is…
the total rest mass of the particles produced.
What is annihilation?
When an antiparticle and corresponding antiparticle collide, causing mass to be converted into energy.
In electron-positron annihilation, why are two photons produced as a product?
To conserve momentum.
___________ can only exist for a fraction of a second before annihilation.
Antiparticles
Describe the properties of an electron antineutrino.
Has zero charge, mass and rest energy.
The repulsion between protons is caused by…
the exchange of virtual photons, which are gauge bosons of the electromagnetic force. The like charges repel one another.
What does virtual mean, if gauge bosons are virtual particles?
Exist for a short time.
What is another name for gauge bosons?
Exchange particles
What is the gauge boson of the weak nuclear force?
W+, W- and Z0
What particles are affected in the strong nuclear force?
Only hadrons
What particles are affected in the weak nuclear force?
All types
The larger the mass of the gauge boson, the ________ the range of the force.
shorter
Does the weak nuclear force have a large range?
No due to the mass of the W bosons
What is the equation of electron capture?
p + e- –> n + Ve
What is the equation of beta-plus decay?
p –> p + e+ + Ve
Are hadrons fundamental?
No, they are made up of quarks.
What is a hadron?
Particles that feel the strong nuclear force.
How many quarks does a baryon have?
3 quarks
Name a baryon.
Proton, Neutron, Sigma
Which is the only stable one?
Proton.
What is the baryon number?
The number of baryons.
What is the baryon number of a neutron?
+1
What is the baryon number of an antiproton?
-1
What is the baryon number of a electron?
0
Is the baryon number conserved in all interactions?
Yes
Name a meson.
Kaon, Pion
Are mesons stable?
No, they all decay.
What is the baryon number of a meson particle?
0
What are the three types of pion?
pi+. pi0 and pi-
Are kaons more stable than pions?
No
Do pions decay into kaons?
No, kaons decay into pions as they have a short lifetime.
Mesons interact with baryons via the _____ force.
Strong nuclear.
Electrons and Neutrinos are classified as…
Leptons
Are leptons fundamental?
Yes
Do leptons feel the strong force?
No
Do leptons interact via the weak force?
Yes
Are muons leptons?
Yes
What are two types of neutrino you need to know?
Electron neutrino and muon neutrino.
The number of leptons is known as…..
Lepton number
What is the lepton number of an electron?
+1
What is the lepton number of a proton?
0
Are quarks fundamental?
Yes
What are the three types of quarks we need to know?
Up, down and strange.
Name a strange particle.
Kaon
Strange particles are created via the _______ interaction but decay via the _______ interaction.
Strong, Weak
Is the strangeness conserved in weak interactions?
No
Are strange particles always produced in pairs?
Yes.
What is the charge of an up quark?
+ 2/3
What is the baryon number of an antidown quark
-1/3
How many quarks are baryons made up of?
3
What is the quark composition of a proton?
uud
What is the quark composition of a neutron
udd
Whats the difference between a baryons particle and antiparticle quark composition?
Antiparticles have three anti-quarks.
What is the quark composition of a meson?
Quark and anti-quark
What is the quark composition of K+
us-
What is the quark composition of K-
su-
What is the quark composition of K0
ds-
What is the quark composition of K0-
sd-
What is the quark composition of pion +
ud-
What is the quark composition of pion 0
uu- or dd-
What is the quark compostion of pion -
du-
In _____ decay a neutron is changed into a proton.
Beta minus.
Name the four properties that are conserved in particle interactions.
Charge, Baryon number, strangeness (only strong interactions) and lepton number.
Is it possible to have a quark on its own?
No
