Lecture 1 Flashcards
what is an atom
it is the smallest particle of an element that still possesses properties of the element
what are the subatomic particles
protons, neurotrons, and electrongs
what is the mass of a neutron or proton
it is 1
what formula relates mass and energy
E=mc2
what is the basic unit of energy
electron volt which is the energy required to move one electron against a potential difference of one volt
does de-excitation occur immediately or take time for electrons
occurs immediately
does de-excitation occur immediately or take time for nucleons
it may be immediate or delayed
what are the classic electron emmissions
characteristic x-ray. auger electron, visible light
what are the emmissions of nucleons
high energy gamma rays or electrons
what is the Bohr model of electrons
electrons resdie wtihin different energy states or levels
what is the k shell hold
2 electrons
what does the L shell hold
8 electrons
what does the M shell hold
18 electrons
what does the n shell hold
32 electrons
when an electron goes from inner to outer does it give off or require energy
requires energy
what is the coulomb force
it is the electrostatic force that keeps the nucleus together.. the protons want to be together
what is the nuclear binding force
attractive force that acts between all nucelar particles at a short distance/ and it dominates
what is binding energy of a nucleus
it is the energy required to voercome the bdining force and remove a nucleon from the nucleus
what is an alternative def of binding energy of nucelus
the energy created when a nucelus is produced from its component parts
what does a high binding energy mean about a nucelus stability
higher menas that its harder to break apart
what is a nuclide
refers to an atom with specific number of protons, neutrons, and nuclear energy state
what does it mean to be radioactive
a nucelide that is radioactive gives off ionizing radiation or particles through the spontaneous disintegration of atomic nuceli
how many elements
118
are nuclides radioactive
no only isotopes are radioactive
what makes some atoms more stable than otehrs
ratio of protons vs. neutrons/ A certain number of neutrons is needed to neutralize the repulsive force of the positively charged protons. More neutrons are needed for heavier elementst
the total number of nucelons, when it is too big it can be hard to old the nucelus together
what is radioactive decay
is the process by which an unstable nucelus transforms into a more stable nucelus by emitting particels adn or photons and releasing energy
is radioactive decay a nucleus or electron process
it is a nucelar process from nuclear instability
what are the modes of radioactive decay
beta negative (negatron emission), positron emission, electron capture, isomeric transition, alpha emission
are energy, charge and mass conserved in decay models?
yes
when does B- decay occur
too may neutrons so ditch it the daughter has an increased z by one
what is the general formula for b-
it is neutron converted into a beta and poroton and energy the new proton stays in the nucelus
what are beta particles used for
imaging with bremmstrahlung breaking radiation. the kinetic energy lost during the braking is emitted as an x-ray and the charged particle is deflected and decelerated
when does b+ decay occur
when there are too many protons. the saughter has one lower Z
what happens to the protons and neutrons and mass when beta+happens
it loses one proton, increases by one neutron, and mass number remains unchanged
what energy must be reached for a positron decay to occur
> 1.022 MeV this is because there will be an excess orbital electron during the decay, this excess electron is released to achieve ground state
what happens to the electron from the emitted positron
it goes throguh an anihilation reaction where the positron collides with an electron and reacts violently. Energy is emitted as two gamma rays in opposing directions.
what happens with electron capture aka when does it happen
it happens when there are too many protons, so there is a proton lost for a neutron, adn this means the z goes down by one
what happens to the total number of protons, neutrons and mass with electron caputre and what is emitted
lose on proton gain one neutron, and mass stays the same. the electron vacancy created will have an emission of a characteristic z-ray or auger electron to fill this in
what determines if electron capture will happen or if positron decay will happen
electron capture and positron decay have the same purpose to reduce the proton to neutron ratio. The transition energy must be >1.022 MeV for positron decay. IF not, only electron capture can occur
what is an isomeric transition and when would it occur
it is would occur if the nucelar energy was too high. It releases some energy
what changes with isomeric transition
it releases a gamma ray or a transfer to electron which is emitted. N ochange of protons or neutrons and there is achange in the energy state overall
when would alpha emission occur
it would occur wit hheavy nucelides and drop portons and neutrons
what is lost with alpha emission
it is two protons and two neutrons
what travels further, alpha, beta, or gamma
gamma goes durtherest distance
which if the three cannot penetrate skin
alpha
what gives the biggest internal dose of radiation
alpha
can gamma rays be imaged
yes gamma camera or SPECT
can positrons be imaged
PET coincidence detection
canbeta neg be imaged
not directly but bremmstralang
can alpha be imaged
no used for the treatment of disease
can electrons be imaged
not directly but could image the things from its decay
is decay predictable
no
what is lambda
it is the decay constat and it is the fraction of atoms undergoing radioactive decay per unit time
formula for the average decay rate
dN/dt=-lambdaN
formula for half life
Ln2/lambda
what is a biological half life
unrelated to the radioactive decay process. IT referse to the time required for 50% of a biochemical to be eleminated from the body
what is the effective half life and formula
it is the disappearance with time of aradioactive biochemical in the body both by radioactivedecay and biological elimination
formula for lambda effective
lambda bio +lambda phys
what is successive decay
a parent nuclide decays to daughter and maybe another adn the daughter goes through own decay and the daughter is also goign through one so succession
what is secular equilibrium
it is when the half-life of parent is much longer than duaghter. The decrease in parent activity is negligible. Daughter nuclide initially builds up due to decay of parent. Reaches maximum acitivity to match that of parent. Both decau with half-life of the parent nuclide
what is transient equilibrium
half life of parent is longer than the daughter by not infinite. the daughter will build up then the daughter activity reaches a maximum that exceeds the parent activity. Ratio of parent to daughter acitivity hits a constant
when does no equilibrium occur
the half life of the parent is shorter than the daughter. No equilibrium between parent and daughter so the daughter builds up, reaches max, then decreases according to the equation. Whne the parent activity is zero, the reamianing daughter half life decays
