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ap physics 2 unit 7

Terms in this set (38)

what do different isotopes of the same element have in common?
same # of protons and electrons; almost identical chemical properties
how are different isotopes of the same element different?
different # of neutrons and atomic masses and mass #s; may have different nuclear properties
the resulting nuclide for gamma (γ) decay is
the same isotope in a lower energy state (in equation, just put same isotope and add γ)
can hydrogen or deuterium emit an alpha particle?
neither can emit an α particle; they can't emit a particle with two protons if they both only have one proton
an isotope has a half-life of one month; after two months, will a given sample of this isotope have completely decayed? if not, how much remains?
no; each month, half of the remaining atoms decay, so after two months only 1/4 of the sample will remain
fission
process in which a larger nucleus splits into two or more fragments, roughly equal is size, releasing energy; protons and neutrons split from nucleus of an atom; used for nuclear reactors and nuclear bombs
fusion
process in which smaller nuclei combine to form larger nuclei, also releasing energy; protons and neutrons added to the nucleus of an atom
why do gamma particles penetrate more easily than beta particles do?
bc they are neutral and have no mass; thus, they don't interact with matter as easily or as often as beta particles do, allowing them to better penetrate matter
does a single photon of infrared light always have less energy than a single photon of ultraviolet light? if so, why?
yes; a photon's energy depends of its frequency E=hf; since infrared light has lower frequency than ultraviolet light, a single IR photon will always have less energy than a single UV photon
does a beam of infrared photons always have less energy than a beam of ultraviolet photons? explain
no; it depends on not only the energy of a single photon but the thickness of the beam (total # of photons in the beam) and the # of particles a second (if both are the same, then yes)
wave model of light
in powerpoint
E = hf
the exact amount of energy in any photon depends on the frequency of the photon
instead of waves, we could consider electromagnetic radiation as a stream of bundles of energy called
photons
α decay
particle containing 2 protons and 2 neutrons; it's a charged particle
β decay
particle just an electron; it's a charged particle
γ decay
no particle, just high energy radiation
how is the half-life of an isotope affected by: pressure increases
not affected
how is the half-life of an isotope affected by: temperature increases
not affected
how is the half-life of an isotope affected by: mass decreases
not affected
particles released during: beta decay
electron, antineutrino
particles released during: alpha decay
alpha particle
particles released during: gamma decay
none
particles released during: positron emission (beta plus)
positron, neutrino
nucleons
protons and neutrons
nuclides
different possible nuclei for an element
radioactivity
emission of a penetrating natural radiation
activity
the measure of radioactivity; the # of disintegrations per second; SI unit is Bq
half-life of a radioactive element
the time needed for half of the atoms to undergo decay
when is the atom considered completely decayed
when there is less than one atom left
unstable/radioactive
every nucleus with more than 83 protons
electron capture
a proton absorbs an inner orbital electron and becomes a neutron and releases a neutrino
the speed of electromagnetic waves in a vacuum
never changes
emission stopped by thin paper or a few centimeters of air
alpha
emission can travel through paper, but is stopped by aluminum
beta
emission can travel through fairly thick lead
gamma
emission is most charged
alpha
emission is heaviest
alpha
charged emissions
alpha/beta plus/beta minus
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