what does the mass number and atomic number of an element represent?
mass number (on top) represents the number of protons and neutrons
atomic number (on bottom) represents the number of protons
atoms of the same element that differ only in their number of neutrons (and so mass numbers will vary)
if an atoms is radioactive it means...?
it is in an unstable form due to a difference in the amount of protons and neutrons (more unstable when protons>neutrons)
these atoms are known as radionuclides
the process an isotope or nuclide undergoes when it is radioactive (it will undergo decay, emmision or ion capture of some sort)
several ways radionuclides undergo radioactive decay
involves the loss of an alpha particle (or a Helium)[42He]
involves the loss of a beta particle, aka an electron [0-1e]
involves the emission of a positron, or a positive electron [01e]
involves the addition of an electron (the conversion of a proton to a neutron)
involves the loss of a y-ray which does not change mass or atomic number but rather energy [00y]
how do you detect radioactivity?
Geiger counter-measures the amount of activity present in radioactive sample ionizing radiation creates ions which conduct a current that is detected by instrument
belt of stability
belt at which an element will be stable
above this belt atom has too many neutrons and will decay by emitting beta particles
below this belt there are too many protons and will stabilize through position emission or electron capture (lighter elements will stabilize via positron emission)
beyond this belt there are too many nucleons and will stabilize through alpha emission
trends in stability
even number of protons and neutrons has most stable isotopes, even number of protons and odd number of neutrons produces less number of stable isotopes, odd number of protons and even number of neutrons creates still less stable isotopes, and odd number of protons and neutrons creates the least number of stable isotopes
cyclotrons and synchrotrons; in order for particles to over come repulsions of nuclei, particles need to be moving extremely fast and collide with the correct orientation so particle accelerators are used to achieve this velocity (the use strong magnets and large electrostatic fields) *this is how most transuranium elements were made (atomic number 92+)
elements that have an atomic number greater than 92 and all are manmade (by bombarding radioactive elements)
equations regarding rate when dealing with radioactivity
(N=number of radioactive nuclei)
units of radioactive decay
1Ci(currie)=3.7 x 1010Bq
described as the number of disintegration per second of a sample
When solving for an energy changes in a radioactive series what equation do you use?
ΔE=Δmc2 c=3.0 x 108 Δm=change in mass ΔE=energy change
how do you calculate the mass change in a radioactive process?
[the mass of the products-the mass of the reactants] theses masses are calculated by adding nucleus mass only (must subtract out mass of electrons if units are in amu[protons=electrons])
units of E=mc2
mass is in kg c is in (m/s)2 if equation provides amu this is g/mol so in order to find kg/nuclide you have to get rid of moles by multiplying g/mol x mol/6.02 x 1023
fission vs fusion
fission involves the bombardment of a radioactive nuclide with a neutron releasing neutrons and causing decay of radioactive nuclide (to create two other radioactive nuclides which will create more)
fusion is a superior method in that it does not involve the production of radioactive nuclides but it requires extremely high temperatures as to overcome nuclei repulsions (plasma is created) and a machine must be created that can withstand these high temps
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