Chapter 1 Flashcards
Protons
Mass
Relative = 1
Kg = 1.67x10−²⁷
charge
Relative = +1
Columns = 1.6x10−¹⁹
Neutrons
Mass
Relative = 1
Kg = 1.67 x10−²⁷
Charge
Relative = +0
Columbn = 0 (neutral)
Electrons
Mass
Relative = 1/1830
Kg= 9.11x10-31
Charge
Relative = -1
Columbn = -1.6x10-19
Specific charge = ?
Charge c / mass kg
Atoms
Specific charge
NO
Electrons + proton = neutron
Nuclei
Specific charge
YES
Protons + neutrons = +ve
Ions
Specific charge
YES
Charged atoms that have lost or gained electrons
Isotopes
Specific charge
NO
Atoms with some number of protons different number of neutrons
Proton
Specific charge
YES
Neutron
Specific charge
NO
The nucleus of a specific charge = nuclide
Elements of atoms
The specific nucleus is described using nuclide notation nucleon number
Top number = proton + neutron
Bottom number = Proton number (proton)
Big letter = atomic number
Isotopes def
Atoms of an element with different number of neutrons and the same number of protons
Specific charge def
Charge / mass value of a charged particle
Why does the nucleus stay together?
There must be a balancing force which counteracts the electromagnets repulsion between protons.
Electromagnets
Electromagnets is a strong force therefore the balancing force must be strong. The force is known as the strong nuclear force.
Large nuclei
Large nuclei are less stable because they are approaching the outer limits of the range of the strong nuclear force.
2 protons and 2 neutrons
Can form their own nucleons and split away from the parent isotope
Alpha decay
Occurs in large nuclei too many both protons and neutrons.
All alpha particle have the same kinetic energy - 5 MeV
Ratio for n:p
Ratio for n:p the nucleus is unstable. The ratio is adjusted by beta decay
Beta decay
Occurs in nuclei which are neutron-rich (have too many). B particles can have a range of kinetic energy. The solution was that a second particles was also emitted and shared the energy so that the total energy was always the same.
Neutrino
The particle was very hard to find because it had little mass and was neutral.
If a nucleus is neutron rich
This allows the rich beta minus decay occurs: neutron changes into a proton it emits an electron an antineutrino
Electron = matter
Antineutrino = antimatter
Look at picture
If the nucleus is proton rich beta plus decay occurs
Proton changes into a neutron which emits a positron and a neutrino
Positron = antimatter
Neutrino = matter
Proton
an elementary particle, that along with the neutron is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron,
Neutron
a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
Has a larger mass than proton and electron
Neutrino
Subatomic particle that is very similar to an electron
No electrical charge
Very small mass
Electron
stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.
Each type of Anti particles and particles
Each type of anti particle has equal mass to its matching antiparticle
A particle and its antiparticle have opposite rest energy.
The charges of a particle and its antiparticle are equal but opposite in magnitude.
Electromagnetic waves
A wave packet or photon consisting of transverse electric and magnetic waves in phase and at right angles to each other.
Photons eq
E = h x f
H = plank constant
Photons
Packet or quantum of electromagnetic waves
Antimatter
Antiparticles that each have the same rest mass and if changed have equal no opposite charge to the corresponding particle.
matter and antimatter
When matter and antimatter particles destroy each other and radiation is released, we make this use of the effect of a positron
Positron
positively charged subatomic particle having the same mass and magnitude of charge as the electron and constituting the antiparticle of a negative electron.
A positron emission takes place when a proton changes into a neutron in an unstable nucleus with too many protons. The positron is the antiparticle of the electron so it carries a positive charge.
1 MeV = what ??
1.60x10-13 Joules
Annihilation
When a particle and its antiparticle meet, they destroy each other and become radiation.
It also occurs when a particle and a corresponding antiparticle meet and their mass is converted into radiation energy. Two photons are produced in this process as a single photon cannot ensure a total momentum of zero after the collision.
Pair production
pair production is when a gamma photon changes into particle and an antiparticle.
It’s the formation of two electrons, ones negative the other one is positive from a pulse of energy travelling through matter.
Eq for pair production
2 x E0 = minimum energy of photon needed
Eg
2 x 0.511 MeV = 1.022 MeV
1.022 x 1.6x10-13 = 1.64x10-13 Joules
Strong nuclear force
Holds particles in the nucleus together
The strong nuclear force between protons outweighs the repulsive electromagnetic force and keeps the nucleus stable.
It doesn’t cause a neutron to change into a proton in beta minus decay or a proton to change into a neutron in beta plus decay, these changes can’t be due to the electromagnetic force as the neutron is uncharged.
Strong nuclear force between o.5 fm and 3.0fm
A strong nuclear force keeps the nuclei stable by counteracting the electromagnetic force of repulsion between protons in the nucleus. It only acts on nucleons and has a very short range attractive up to the separation of 3.0fm, but the repulsive below separations of 0.5fm.
Weak nuclear force
Force responsible for beta decay
The weak nuclear force (or just the weak force, or weak interaction) acts inside of individual nucleons, which means that it is even shorter ranged than the strong force. It is the force that allows protons to turn into neutrons through beta decay. This keeps the right balance of protons and neutrons in a nucleus. The weak force is very important in the nuclear fusion that happens in the sun.
Neutrino
A neutrino can interact with a neutron and it can make it change into a proton. A beta minus particle (an electron) is created and emitted as a result of the change.
ANTINEUTRINO
An antineutrino can interact with a neutron and make it change into a neutrino. A beta plus particle (a positron) is created and emitted as a result of the change
W boson
A carrier of the weak nuclear forceL; W bosons have non zero rest mass and may be positive or negative.
Unlike photons these exchange particles
Have a non zero rest mass
Have a very short range of no more than about 0.001fm
Are positively charged (W+ bosons) or negatively charged (W- boson)
-w boson
Decays into beta decay particle and an antineutrino
W + boson
Decays into a beta + particle and a neutrino
Beta minus decay
In beta minus decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino; while in beta plus (β+) decay, a proton is converted to a neutron and the process creates a positron and an electron neutrino. β+ decay is also known as positron emission.
Beta plus decay
During beta-plus decay, a proton in an atom’s nucleus turns into a neutron, a positron and a neutrino. The positron and neutrino fly away from the nucleus, which now has one less proton than it started with. Since an atom loses a proton during beta-plus decay, it changes from one element to another.