Section 1- Particles And Radiation Flashcards
1)What are protons and neutrons called?
2)what is the charge and mass of protons, neutrons and electrons?
1)nucleons
2) use relative charge and mass as the values are too small
1)What is the proton number/ atomic number?
2)what is a neutral atom?
3)what can the proton number show us?
1)number of protons in the nucleus, it defines the element, no two different elements will have the same number of protons
2)number of electrons equals the number of protons.
3)reactions and chemical behaviour depend on the number of electrons.
1)what is the nucleon number?
2)what is the nuclide notation?
1)mass number, tells you how many protons and neutrons there are, (tells you a good approximation of mass)
2)summaries all the information about an elements atomic structure
1)What is specific charge?
2)what is a fundamental particle?
3)how to calculate specific charge?
4)what is the equation for specific charge?
1)specific charge of a particle is the ratio of its charge to its mass, given in coulombs per kilogram (C kg -1)
2) a particle that cannot be split up into anything smaller e.g electron
3)
1- find the number of nucleons (mass number) and multiply by it’s mass to find the mass of the atom
2-multiply the amount of protons by its charge
3-then divide them
(Mass of electrons are ignored as they very small, the charge is still accounted for so make sure include positive and negative symbols)
NEVER INCLUDE PROTON CHARGE
4)
1)what are isotopes?
2)how does different number neutrons affect an atom?
3)what do unstable nuclei do to become more stable?
1)Atoms with the same number of protons but different numbers of neutrons
2)neutrons affects the stability of the nucleus. greater the number of neutrons compared with the number of protons, more unstable the nucleus.
3)may be radioactive and decay to make themselves more stable
1)what is isotopic data?
2)what is an example of isotopic data?
1)the relative amounts of different isotopes of an element present in a substance
2) living things contain isotopes of carbon. The percentage of carbon which is radioactive carbon-14 (taken in from the atmosphere) is the same in most living things. After they die, the amount of carbon-14 inside them decreases over time as it decays to stable elements.
-Scientists can calculate the approximate age of archaeological finds made from dead organic matter (e.g. wood, bone) by using the isotopic data to find the percentage of radioactive carbon-14 that’s left in the object.
1)name the free forces that act on the nucleons?
2)what does the electromagnetic force do?
3)what does the gravitational force do?
4)what does the strong nuclear force do and why do we need it?
1)electromagnetic force, gravitational force, strong nuclear force
2)causes positively charged protons in the nucleus to repel each other
3)causes all the nucleons in the nucleus to attract each other due to their mass
4) the repulsion from the electromagnetic force is bigger than the gravitational attraction. If these were the only forces acting in the nucleus, the nucleons would fly apart.
-strong nuclear force=attractive force that holds the nucleus together (must be stronger than the electromagnetic force)
1)what are limitations to the strong nuclear force?
2)How does the strong nuclear force work on the nucleons?
3)can you explain this graph? (3)
1) it has a very short range and can only hold nucleons together up to a few femtometers, (struggles to hold together large nuclei which makes them unstable)
-At very small separations, the strong nuclear force must be repulsive otherwise there would be nothing to stop it crushing the nucleus to a point.
2)equally
3)
1-The strong nuclear force is repulsive for very small separations of
nucleons (less than about 0.5 fm).
2-As nucleon separation increases past about 0.5 fm, the strong nuclear force becomes attractive. It reaches a maximum attractive value, and then falls rapidly towards zero after about 3 fm.
3-The electromagnetic repulsive force extends over a much larger range (infinitely, actually).
1)What is nuclear decay?
2)why does alpha decay happen in very big atoms (uranium)?
3)what happens in alpha decay?
1)unstable nuclei will emit particles to become more stable
2)nuclei of these atoms are just too big for the strong nuclear force to keep them stable. more stable=they emit an alpha particle, (helium atom) from their nucleus.
3)When an alpha particle is emitted the proton number decreases by two and the nucleon number decreases by four
1)how can you show that alpha partials have a short range?
1)few cm in air.
1-observing the tracks left by alpha particles in a cloud chamber
2-Geiger counter or a spark counter. (measure the amount of ionising radiation). up close to an alpha source and then move it away slowly, you’ll see the count rate will drop within a few centimetres.
1)What is Beta-minus (B-) decay?
2)when does beta decay happen?
3)what happens when a nucleus ejects a beta particle?
4)how does equation change?
1)emission of an electron from the nucleus along with an antineutrino particle.
2)happens in isotopes that are “neutron rich” (i.e. have too many neutrons compared to protons in their nucleus).
3)one of the neutrons in the nucleus is changed into a proton. antineutrino particle released carries away some energy and momentum.
1)what range can beta particles travel?
2)what did scientist originally believe about beta decay?
3)In 1930 who suggested another particle was being emitted?
4) what were the main conditions that this particle had to fit? (2)
1)serval meters through air
2)only particle emitted from nucules was an electron, however, observation show that the energy of the particles after the beta decay was less than it was before which doesn’t fit with the conservation of energy
3)Wolfgang Pauli suggested another particle was being emitted and carried away the missing energy (neutrino/antineutrino)
4)
1-had to be neutral or the charge wouldn’t be conserved in beta decay.
2-had to have zero mass, as it has never been detected
Describe how the strong nuclear force between two nucleons varies with the separation of the nucleons quoting suitable values for separation?
-Two nucleons experience attraction between 0.5 fm and 3 fm.
-beyond 3fm is 0 force. Below 0.5 fm is repulsion.
-short range
Which ionizing radiation produces the greatest number of ion pairs per mm in air?
Alpha
Typical maximum range in air for α and β particles and y?
Alpha= 0.04 m
Beta= 0.40
Gamma=1km
γ rays have a range of at least 1 km in air.
However, a γ ray detector placed 0.5 m from a γ ray source detects a noticeably
smaller count-rate as it is moved a few centimetres further away from the source. Explain this observation.
reference to the inverse square law of (γ radiation)
reference to lowering of the solid angle (subtended by the detector as it moves away)
radiation is spread out (over a larger surface area as the detector is moved away)
Following an accident, a room is contaminated with dust containing americium which is an α−emitter.
Explain the most hazardous aspect of the presence of this dust to an unprotected human entering the room.
dust may be ingested / taken into the body / breathed in
causing (molecules in human tissue / cells) to be made cancerous / killed
damaged by ionisation
How do you draw this graph?
graph passes through N = 10/11 when Z = 10 and N increases as Z
increases
N = 115 - 125 when Z = 80 and graph must bend upwards
A particular nuclide is described as proton-rich. Discuss two ways in which the nuclide may decay?
β+
describe the changes to N (up by 1) and Z (down by 1) [or allow p change to n]
α
move closer to line of stability [or state the proton to neutron ratio is reduced]
p
only if nuclide is very proton rich
[or electrostatic repulsion has to overcome the strong nuclear force] [or highly unstable] [or rare process]
e– capture
describe the changes to N (up by 1) and Z (down by 1) allow p changes to n
What are constituents?
component part of something
Which constituent of an atom has the largest charge-to-mass ratio?
Electron
What constituents have zero charge per unit mass ratio?
Neutron
Which constituents have the largest charge per unit mass ratio?
electron
State what is meant by the specific charge of a nucleus?
The ratio charge to mass in nucleus
1) nucleon number?
2)
1) total number protons and neutrons in nucules
2)number of neutrons less
mass the same
but more protons therefore greater charge
1)Charge of an alpha particles?
2)Describe the symbols of the proton and nucleon number?
3)What are isotopes and how do their chemical and physical properties differ?
1) Alpha has a charge of 2+ because it has two protons (helium nucleus)
2) Proton number (atomic number) z
Nuculeon number (mass number) a
3) Isotopes of an element have same number of electrons so the same chemical properties.
The atoms have different masses so their physical properties are different
1)What is protium, structure and uses?
2)What is deuterium structure and uses?
3)what is tritium structure and uses?
1) Protium is a hydrogen atom with 1 proton and 0 neutrons. 99.98% of hydrogen atoms are protium.
used in hydrogen fuel cells and the production of plastics.
2)Deuterium is a hydrogen atom with 1 proton and 1 neutron. Around 0.02% of hydrogen atoms are deuterium. used in nuclear fusion.
3)Tritium is a hydrogen atom with 1 proton and 2 neutrons.very rare. used in thermonuclear fusion weapons.
1)what is nuclide (protons)?
2)How can you calculate the age of fossils?
1) ->nuclide specific nucleus that contains a certain number of protons, neutrons. Same number electrons
E.G: carbon nuclide with 6 protons and 6 neutrons is different to a carbon nuclide with 6 protons and 7 neutrons. But, both are isotopes of carbon.
2)
1.All living organisms have the same amount of carbon-14 atoms as percentage of all carbon isotopes.
2.Once the organism dies, it no longer absorbs carbon from the atmosphere.
3.Carbon-14 is radioactive and so will decay over a known half life.
3.older a fossil is, the fewer carbon-14 isotopes it will contain and the less radiation it emits.
1)what is the nuclear diameter and how was it found?
2)Equation for radius of nucleus?
1) -Radius of a nucleon is 1.2x10^-15 m to 8x10^-15 m (experiments using high energy electrons.)
2)
1)Equation for nuclear density?
1) Mass nucules/ volume
-> all nuclei have about the same density
1)Describe a brief overview of the summary history atom?
1)
-> Democritus=things could be cut into even smaller species called atoms (smallest indivisible piece something could be cut into)
->John Dalton= atoms to be tiny and invisible
-> JJ Thompson discovered the electron (smaller than the atom-sub atomic particle) 1897 (sphere of positive charge with electrons in it- plum pudding model. Electrons were allowed to move throughout in ringed orbits .
->1980s researchers at IBM produced a machine called an atomics force microscope able to image individual atoms
1)what did the Rutherford scattering experiment prove?
2)Describe how the Rutherford scattering was performed?
1) Proved nucleus is 5000 times smaller than the atomic radius in 1911
-modern version is nuclei diameter 10^15 m, Rutherford calculated 10^14 m
2)
->fired positively charged alpha particles at very thin gold foil observing how they scattered
->tiny flash of light was seen through microscope each time a scattered particle struck the zone nc sulphide screen.
->microscope could be rotated around the foil, different angles to the path of the incident beam of a-particles.
The number of a-particles hitting the screen at each angle could then be counted.
1)what does the strangeness (symbol s) mean?
2)what two things are conserved in interactions?
3)Quark symbols for protons and neutrons and their antiparticles?
1) quantum number to reflect the fact that strange particles are always created in pairs.
2) recognise that energy and momentum are conserved in interactions.
1)what is the muon symbol?
1)what is the muon neutrinos symbol?
1)what is the symbol of electron neutrinos?
1)What does a nucleus above the stability do?
2)what does a nucleus below the stability do?
3)How do heavy nuclei decay?
1)what do you use when identifying elements?
2)A particles energy and where this comes from?
3)why does alpha particles have most of the energy?
4)Alpha decay equation?
1) ->Don’t use mass number it could be an isotope, use proton number
2) ->a-emitting nuclides eject most their a-particles single energy value, characteristic of the nuclide.
-> a-particle most of the energy (ke). a-particle, daughter nucleus, which recoils.
3) much higher velocity than recoiling nucules carries away most of the kinetic energy.
1)what is the Beta - decay equation and description?
1)what is the equation and description for beta + decay?
1)How can a decay series be presented?
1) ->Uranium goes through a series of decay processes eventually lead to lead. Can be plotted on charts.
1)alpha, beta, gamma, neutrino, antineutrino symbols?
2)When something decay by gamma what symbol is added?
2) decay via gamma ray emission have the letter ‘m added after their nucleon number, meaning metastable’. technetium-99m
1)what do you measure energy in?
2)How does ionisation work?
1) measure their energy in electron volts (eV)
2) radiation lonises molecules by ‘knocking’ electrons off. energy is transferred from the radiation to the material.
1)Alpha, Beta, Gamma properties?
1)what is exponential decay?
2)when does predicted decay become unreliable?
1) exponential decay curve because the number dice atoms falls by the same fraction (y) after each throw.
2) the results are unreliable after 8 throws because the sample is too small, becomes impossible to predict the number that will decay in each throw
1)How to investigate the inverse square law?
2)what do you find out about the inverse square law?
1)
1->investigate the inverse square law using the apparatus the diagram.
2->measure the background count rate.
3->start with the y-ray source close to the G-M tube and measure he count rate.
4-> increase the distance between the source and the the and record the corrected count rate
2)
1)when does the inverse law apply?
2)Explain and give an example of the inverse square law?
1) Inverse-square law applies to a and B-rays in a vacuum, but not in air:
-Unlike y-radiation, the air absorbs both a and B-radiation.
2) ->v-rays spread out from the source and so fewer rays enter the tube as it is moved away from the source.
->double the distance between the source and the tube the count rate falls to ¼.
1)What do LEDs do and what can we had them for?
2)Who made the theory of photons and why?
3)what was the concept called?
4)What do atoms absorb and emit?
5)what is planks equation mixed with wavelength to get energy?
1) -> Light-emitting diodes (LEDs) emit light when a current flows. Using LEDs, we can find the Planck constant h.
2) 1900 Albert Einstein and Max Planck theory of photons to account for some experimental observations that could not be explained otherwise, including the photoelectric effect.
3) concept of a fundamental unit of energy, (quantum.)
4) emit radiation in multiples of discrete amounts that are given by the Planck equation: E= hf
1)Name all the wavelengths, waves in EM spectrum?
1)Describe the process of the practical of the photon model?
1)How do you plot a graph for photon model of Electromagnetic radiation?
1)
1)How to calculate energy emitted per second (output power) of the LED when you know the amount of protons emitted per second?
2)LEDs need to be connected to a minimum voltage before they emit light. Explain why a red LED needs lower voltage than a blue LED?
1)
(Light photons energy)x(photons emitted per second)
2)
.red longer wavelength
.smaller energy is required and smaller PD required
.E=QV so smaller voltage needed (lower voltage lower energy)
-> meters to nm x10^9 or divide by 10^-9
-> use the powers of 10
