test 2
how many atomic units is a proton and neutron
1
how many atomic units is an electron
0 as their so small in mass in comparison
one nucleus is what
a nuclide
what letter represent the atomic number
Z
what letter represents nuetron number
N
what letter represents mass number
A
what are the properties of an isotope
diff physical properties but identical chem properties (how they interact)
what is a radioisotope
when the nucleus of an isotope become unstable it may undergo radioactive decay or transmutation
radiation is emitted
where are the radioactive isotopes
>82 protons (bismuth and above) as well as TC (43) and Pm(61)
what is nuclear decay
any change to the nucleus of an atom
-diff from chem reaction as thats only electrons
similarities between radioactivity, radioactive decay and nuclear decay
all the same thing!
what is alpha decay
the loss of 2 protons and 2 neutrons
what is beta decay
the lose of 1 electron is minus as a neutron turns into a proton
the lose of 1 antielectron (positron) (proton basically)
what is gamma decay
the release of gamma particle (y) from high energy nucleus (too high so releases gamma)
what is y
a photon of electromagnetic radiation (light) which is a gamma ray
properties of gamma
no mass or charge
what is penetrating ability
the tendency for radiation to pass through metalsd instead of being blocked (higher means pass through higher density)
what is ionising ability
the tendency for radiation to ionise materials by adding or removing electrons
how is ionising harmful
turns the material into ions which fundementally changes the biological material of something
properties of alpha particles
slow
double positive charge loss
high concentration
high ionising
low penetrating
why do alpha particles slow down so quick
little energy is passed onto interacting atoms every time meaning it slows down for every interaction
eventually slow enough to gain two electrons and become helium or smt
properties of beta decay particles
fast
negative charge loss
repelled by valence electrons bc negative
ok on surface of people but bad if inside
why is beta faster than alpha
has glancing collisions due to repulsion but is slowed down less per interaction than alpha
also occasionally dislodged electrons if at correct angle
properties of gamma
very fast
no charge
only interacts if direct collision w/nucleus/electron which is rare
low ionising
high penetration
what are each of the decays stopped by materials
a=paper
B=aluminium
y=lead
what is half life
the time is takes for hald a radioactive substance to decay
measured in time
equation for half life without n
N=N0(1/2)^t/t(1/2)
N0 is original mass/number
t is time passed
t(1/2) is time for half life
equation for half life eith n
N0(1/2)^n
n is how many half lives occured
how to find half life on a graph
look at half the original # of particles
look at the time
is uncertain, half it
what is activity
the word used to describe the frequency of decay
what is activity measured in
Becquerels or Bq
what is one Bq
1 decay per second
equation for activity
A= A0 (1/2)^n
what is nueclear force
the repulsion then attraction of nucleons
first so they dont compress too much
then so they dont repulse and fuck up the nucleus
if a large distance between protons in nucleus, what happens
the repulsion is stronger than the nuclear force
what is an electronvolt
a very small unit
how to find an electron volt
eV= Joules/1.6 x 10^-19 (charge of electron)
what is mass defect
the mass lost when the protons and neutrons combine (they share mass like siamese twins)
what is binding energy
the energy required to fulfill the neutrons and protons when splitting the nucleus into the individul atoms
what is the equation for binding energy
E= m c^2
m is mass
E is energy in joules
c is speed of light (3x 10^8)
higher stability in binding energy means what
higher binding energy
thus more mass shared/lost when combined
what is fission
when a nucleus is struck by a neutron and the substance splits into two nuclei, neutrons and energy
how do chain fission reactions occur
when the fission occurs, neutron(s) fly off and hit another nucleus and assuming it can produce fissile fragments (has critical mass(enough mass to split)) then another fission reaction occurs
binding energy definition
the energy required to split an atom into all individual neutrons and protons separately
what is fusion
pushing atoms close enough to form a bond
what does fusion require
high pressure and temp
eV to J conversion
J= eV x 1.6 x 10^-19