Chapter 11 & 12 Flashcards
What two types of particles does the nucleus contain?
Protons & Neutrons
The number of protons in the nucleus is given by…
the atomic number, Z.
The neutron number, N, is the…
number of neutrons contained in a nucleus.
The mass number, A, is the…
total number of protons and neutrons in a nucleus.
Protons and neutrons are collectively referred to as
nucleons
_______ of a given element have the same number of protons in the nucleus but a different number of neutrons.
Isotopes
The 4 fundamental forces
1) Gravity -binds planets to the sun
2) Electromagnetic Force - binds atoms and molecules
3) Weak nuclear force - produces beta decay
4) Nuclear Strong Force - binds the nucleus.
Isotopes with unstable nuclei are called
radioisotopes
Radioactivity, also called radioactive decay, occurs when…
an unstable nucleus emits radiation.
_______ is helium-4 nuclei.
alpha radiation
_______ is high energy electrons.
beta radiation
_______ is EM radiation.
gamma radiation
when an unstable nucleus ejects a helium nucleus, two protons and two neutrons.
Alpha decay occurs
When an unstable nucleus ejects an electron.
Beta decay occurs
When an excited nucleus ejects a photon.
Gamma decay occurs
List the types of radiation in order of least difficult to stop to most difficult to stop.
alpha, beta, gamma
Which type of radiation is most difficult to stop?
Gamma radiation
When does radioactive decay occur?
Spontaneously
At random
But predictably – like how many times you get 11 after thousands of rolls.
The time it takes for half the nuclei in a sample of a radioisotope to decay.
Half-life
______ uses the decay-rate of carbon-14 to determine how long ago an organism died.
Carbon-14 dating
_______ is naturally created when thermal neutrons in the upper atmosphere bombard N-14.
C-14
Considered the fatal dose of radiation.
6 Sv or Gy
Something harmful at high doses is beneficial at low doses.
hormesis
Implant Radiation Therapy. Radioactive “seeds” placed directly into a cancer tumor.
Brachytherapy
Almost all modern “external beam” radiation therapy is done with…
linear accelerators
Patient is injected with radioactive isotopes which emit positrons – which collide with electrons to produce gamma rays.
PET Scans
______has best spacial imaging.
CT scans
______has best functional imaging.
PET Scans
The process of multiple treatments over several days.
Fractionation
The speed of light
c = 3 * 10^8 m/s
The laws of physics are the same for all observers moving uniformly.
- The 1st postulate of special relativity
- aka: the principle of relativity
The speed of light is a fundamental constant of nature.
The 2nd postulate of special relativity states:
Why is the special theory of relativity “special?”
Because it is restricted to uniform motion.
you observe the clock of someone moving, relative to you, to run slower than your clock.
Time dilation
you observe the length of an object moving, relative to you, to be less than an identical object at rest, relative to you.
Length contraction
This is the apparent shortening of moving objects in the direction of their motion
Length contraction
The Universe was created and time began when a point source singularity of “infinite” mass “exploded”
The Hot Big Bang Theory
represents a lower frequency due to the Doppler Effect, showing the universe is expanding.
redshift
Results in a drastic change in the mass of the nucleus.
Alpha decay
