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147 Cards in this Set
- Front
- Back
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What is mass?
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-Measure of a body's inertia or resistance to acceleration
-kg |
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What is velocity?
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constant speed of a body moving in a given direction
m/s |
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What is Accerleration?
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Rate of change of velocity
m/s2 |
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What is force?
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causes a body to deviate from a state of rest or constant velocity
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Equation for force:
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Force=mass x acceleration
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What are the 4 physical forces in the universe?
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-Gravitational
-Electrostatic -Strong -Weak |
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What is gravity?
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-Pulls objects to the earth
-often ignored in physics |
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What is electrostatic force?
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Casues protons and electrons to attract each other; holds atoms together
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What are strong forces?
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Holds nucleus of an atom together
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What are weak forces?
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Involved in beta decay
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What is energy?
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The ability to perform work
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Formula for KE?
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1/2mv2
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Formula for PE?
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mxgxh
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What did einstein's equation show?
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Energy and mass are interchangeable
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What is enistein's equation?
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E=mc2
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What is 1 electron volt in joules?
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1.6x10-19 J
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What is power?
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Rate of performing work
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What is power measured in?
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j/s
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What is the electrical charge of electrons and protons?
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1.6x10-19 cooulomb
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What is the + part of the electrical circuit?
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Anode (A+)
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What is the -part of the electrical circuit?
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Cathode (C-)
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What is electric current?
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Flow of electrons through a circuit (amps)
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Formula for amps
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C/sec
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Formula for Power
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P=IxV
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What is matter?
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Protons, neutrons, electrons
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What atomic particles are stable and unstable?
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Stable-protons and electrons
Unstable-neutrons, half life 11 minutes |
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What is atomic number (Z number)
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Number of protons in the nucleus
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What is the mass number (A)
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protons +neutrons in the nucleus
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What is 1 amu equal to?
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1.6x10-27 kg
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What is the mass of protons and neutrons?
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1 amu 1.6x10-27kg
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What is the mass of an electron?
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9.1x10-31 kg
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What is avagadro's number?
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6x1023 atoms one gm mole of a substance or N0
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What are nucleons?
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The nucleus of an atom made up of tightly bound protons and neutrons
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What formula determines the number of electrons in the electron shells?
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2n^2
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What is the bohr model?
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Electrons surrounding the nucelus in shells
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What is the Z/A of a atoms of most substances making up humans?
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0.5
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How are electrons held in place
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Electrostatic pull of + charged nucleus
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What is the work required to removed an elecron from an atom
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electron binding energy
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What is the binding energy of outer shell e- to inner shell e-
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outer shells BE small while inner shell BE large
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What happens when e- move from outer shell to inner shell?
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emit excess energy as electromagnetic radiation
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What atomic particles are stable and unstable?
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Stable-protons and electrons
Unstable-neutrons, half life 11 minutes |
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What is atomic number (Z number)
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Number of protons in the nucleus
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What is the mass number (A)
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protons +neutrons in the nucleus
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What is 1 amu equal to?
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1.6x10-27 kg
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What is the mass of protons and neutrons?
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1 amu 1.6x10-27kg
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What is the mass of an electron?
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9.1x10-31 kg
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What is avagadro's number?
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6x1023 atoms one gm mole of a substance or N0
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What are nucleons?
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The nucleus of an atom made up of tightly bound protons and neutrons
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What formula determines the number of electrons in the electron shells?
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2n^2
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What is the bohr model?
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Electrons surrounding the nucelus in shells
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What is the electron density of a substance of most substances making up humans?
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0.5
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How are electrons held in place
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Electrostatic pull of + charged nucleus
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What is the work required to removed an elecron from an atom
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electron binding energy
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What is the binding energy of outer shell e- to inner shell e-
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outer shells BE small while inner shell BE large
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What happens when e- move from outer shell to inner shell?
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emit excess energy as electromagnetic radiation
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What determines the chemical properties of an electron?
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Number of electrons in the outer shell-valence electrons
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What is the electron density of atoms making up a humans?
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~0.5
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What holds atomic electronsin places?
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Electrstatic pull
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What is the electron binding energy?
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The work required to remove an electron from an atom
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Compare the binding energy of the outer shell electrons and inner shell electrons
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BE of outer shell smaller than inner shell
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What happens when electrons move from outer energy shells to inner shells
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Emit excess energy as electromagnetic radiation
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How are nucleons held together?
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strong forces
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What is the total binding energy of the nucelsu?
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Energy requred to separate all the nucleons
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What is the binding energy of a single nucleons?
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Energy requried to remove it from the nucleus
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What is the average binding energy per nucleon?
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total binding energy divided by the number of nucleons
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What does a high nuclear binding energy indicate?
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nuclear stability
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What happens to the average binding energy per nucleon after radioactive decay?
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It increases b/c the daughter is more stable than the parent
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What is the wavelength?
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Distance b/w successive crests of waves
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What is amplitude
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Intesity defined by the heights of the waves
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What is the frequency?
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number of wave oscillations per unit time
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What is the period
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time required for one wavelength to pass
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What is the speed of light?
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freq. x wl of EM radiation
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What does EM radiation being quantized mean?
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Exists in discrete quantities of energy called photons
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what are photons
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can behave as waves or particles but have no mass
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What is photon energy equal to?
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Directly porportional to freq. and inv. proportional to wavelength
E~f E~1/wl |
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What is the formula for the Energy of a photon?
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E=hxf
or E=h x (c/lambda) h=plank's constant means the greater the energy, the lower the wavelenth and higher the frequency |
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What is the inverse square law?
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-x-ray beam intensity (I)DECREASES with increasing distance from the tube (x1 is distance 1 and x2 is distance 2)
-I~(x1/x2)^2 |
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What is ionization?
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Occurs when an electron is ejected froma neutral atom, leaving behind a positive ion
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What is ionizing radiation?
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Electromagnetic radiation with sufficient energy to remove electrson
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What are the two types of ionizing radiation?
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x-rays and gamma rays
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What is directly ionizing radiation?
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Involves charged particles-electrons, positrons, protons, alpha particles
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What is indirectly ionizing radiation?
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Involves uncharged particles like neutrons, x-rays, gamma particles
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What is the average amount of energy needed to generate one electron-ion pair in air
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33 eV
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How do charged particles lose energy?
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When they pass through matter by interacting with electrons in nearby atoms
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The loss of energy by a charged particle increases with what?
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-Increasing charge and mass
-Decreasing particle velocity |
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What can energy lost from energetic partcles do?
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-Eject electrons from atoms
-raise atomic electrons to higher energies |
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What is linear energy transfer?
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Measures the loss of energy of a charged particle in thousands of electron volts for each micrometer of distance traveled by the particle.
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How much energy do electrons and positrons lose when traveling through 1 um of tissue?
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-0.5 KeV
-Low LET radiation |
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How much energy do alpha particles lose when traveling through 1 um of tissue?
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-100 kEV
-high LET radiation |
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What is LET of neutrons and protrons
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in b/w electrons & positrons and alpha particles
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What is energy depostion by radiation ultimately transformed to?
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Increased molecular motion (heat)
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Is the heating effect of ionizing radiation in radiology significant?
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No its negligible
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What are nulcides?
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Nuclei haing a different number of protons, neutrons, or both
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What are radionuclides?
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Unstable nuclides
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What are isobArs?
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nuclides with the same mass number (A)
**top number is the same |
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What are istoPes?
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nuclides with the same number of protons (P)
**Bottom number is the same |
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What are isotoNes?
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nuclides with the smae number of Neutrons (N)
**neither number is the same |
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What are isomErs?
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Excited state of a nucleus
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What is the mass number (A) equal to?
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A=P+N
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In common, stable, low mass number nuclides what is true?
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Neutrons~=Protons
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IN common, stable high mass number nuclides, what is true?
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Neutrons>Protons
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What are the three processes by which unstable nuclide or radionuclide attains stability?
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-Alpha, beta, gamma decay
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What is the transformation from unstable to stable nuclide called?
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Radioactive decay
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What is conserved in nuclear transformations?
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Energy, mass number, and electric charge
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What is the radioactive half life defined as?
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Time for half the materal to decay
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What is the activity defined as?
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Number of transformation per unit time
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What is the relatioship b/w the decay constant (lamda) and half-life?
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lamda=0.693/t(1/2)
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What are gamma rays?
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High energy photons that result from the nuclear processes
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What is the ground state?
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The lowest energy state of a nucleus and the MOST STABLE arrangmeent of nucleons
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What is an excited state?
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-Increased energies
-Unstable -Have a transient existence before transforming to a more stable state |
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what is a metastable state?
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-Isomeric state
-Unstable -Relatively long half-life before transfomring to another state |
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How long does the half life have to be before its called the metastable state?
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>10^-12 seconds
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How do you denote the metastable state?
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a small "m" like Tc99m
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How do you release gamma rays?
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Nuclear transformations to a more stable state (isomeric transitions) release energy as gamma rays
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What may also happen instead of emiting gamma rays?
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Energy transfrred to an orbital electrons-->this is then emitted from the atom as an internal conversion electron
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Describe beta minus decay:
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Neutron inside the nucleus is converted to a protonand excess energy is released as an energetic electrons called (Beta particle) and an antineutrino
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asdfsdfasd
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asdfasdf
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Characteristics of an antineutrino?
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-No rest mass
-No electric charge -rarely interacts with matter |
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When does Beta minus decay occur?
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In nuclei with too many neutrons
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What happens to the atomic number and mass number in beta minus decay?
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Atomic number increases by one, mass number is the same
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What are the relative energies of beta emitters?
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There is a range up to Emax; average energy of beta emitters is ~ 1/3Emax
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What is Beta plus decay?
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-Proton in the nucleus is converted to a neutron and energy emitted as a + charged electron (positron) and a neutrino
-Called positron emission |
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What are the characteristics of a neutrino?
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No electric charge, no rest mass, similar to an antineutrino
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What is a positron?
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Electron with a positive charge instead of a negative charge and interacts with matter like an electron
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When does Beta + decay occur?
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In nuclei with too few neutrons
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What happens to the atomic number and mass number is beta + decay?
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Atomic number goes down by 1 and mass number stays the same
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How do energetic positrons lose their energy?
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By ionization and excitation of atomic electrons
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What happens when a positron loses all its energy?
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It annihilates with an electron
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Describe the anhilation reaction:
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The mass energy of the postron and the electron (511 keV each) is converted into two 511 keV PHOTONS that are emitted 180 degrees apart
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What is the relative half lives of positron emitters?
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Relatively short
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What is electron capture?
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Proton inside a nucleus is converted into a neutron by capturing an electron from one of its shells
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What is emitted in electron capture?
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A neutrino and x-rays
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What shell is electron capture most likely from?
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K-shell, follwing by L-shell, then M-shell etc
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What type of nuclei does electron capture occur in?
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Those with too few neutrons (too many protons)
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what happens to the atomic number and the mass number in electron capture?
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Atomic number decreases by 1 and mass number stays the same
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Ex: What happens when electron capture is from a K-shell?
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K-shell vacancy filled by electron from an outer shell
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How is excess energy emitted in electron capture?
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1. Characteristic x-ray
2. Auger electron |
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What is the energy of the Auger electron equal to?
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Characteristic x-ray energy-Electron binding energy
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What may electron capture compete with?
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Beta+ decay
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What are some impt electron capture radionuclides used in nuclear medicine?
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Co 57
Ga 67 In 111 I 123 I 125 TI 201 |
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What is alpha decay?
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Radionuclide emits an alpha particle consisting of 2 neutrons and 2 protons (a helium nucleus) He 4/2
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In what atoms is alpha decay most common?
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With atomic number (Z)>82
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What does Ra226 (Radium) decay to by alpha decay?
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Ra222 (Radon)
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What happnes to the atomic number and the mass number is alpha decay?
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Mass number decreases by 4 and the atomic number decreases by 2
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What are the relative energies of alpha particels?
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b/w 4 and 7 MeV
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How far do alpha particles travel in:
1. air 2. Tissue |
1. 1 to 10 cm in air
2. 0.1 mm in tissue |
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So when do alpha particles pose a great risk?
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If injested or injected but not as external radiation
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