Nuclear Chemistry
nucleon
the collective terms for protons and neutrons
nuclide
an atom (in nuclear chemistry)
Uranium-238
one way to represent uranium with a mass of 238 in nuclear chemistry
top: mass & bottom: atomic number
one way to represent a nuclide
mass defect
the difference between the mass of an atom and the sum of the masses of the subatomic particles
how to find mass defect
take the mass value and the atomic number to determine how many protons and neutrons. Multiply each amount by their respective weights and add to find the subatomic particles mass. Then take the given actual mass and subtract to find the mass defect
E=mc²
formula to find energy used to hold nucleus together, called binding energy
binding energy
the energy released when a nucleus is formed from nucleons
binding energy per nucleon
the binding energy of the nucleus divided by the number of nucleons it contains
band of stability
the stable nuclei cluster over a range of neutron-proton ratios (1 to 1 for small nuclei, 1.5 to 1 for large nuclei)
nuclear shell model
states that nucleons exist in different energy levels or shells in the nucleus
magic numbers
the number of nucleons that represent completed nuclear energy levels
nuclear reaction
a reaction that affects the nucleus of an atom
transmutation
a change in the identity of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation, or both
nuclear radiation
particles or electromagnetic radiation emitted from the nucleus during radioactive decay
radioactive nuclide
an unstable nucleus that undergoes radioactive decay
alpha particle (α)
symbol: ⁴₂He. the nucleus of a helium atom + no electrons. Results in a decrease in mass and atomic number
beta particle (β)
an electron. Has virtually no mass and has a negative charge. It is emitted when fission occurs and results in an increase of atomic number only
gamma particle (γ and ⁰e)
a very high energy photon that does not affect the mass or the atomic number of an atom
positron emission (⁰₋₁e)
a particle with the mass of an electron but with a positive charge. An atom emits this in an effort to stabilize and this converts a proton into a neutron, decreasing the atomic number by 1.
k-electron capture
same symbol as positron emission. the only case where a particle will be a “reactant” as opposed to a “product”. This particle is an electron pulled into the nucleus and results in a decrease in atomic number, but is different from positron emission
nuclear fission
occurs when a very heavy nucleus splits into more-stable nuclei of intermediate mass
chain reaction
a reaction in which the material that starts the reaction is one of the products
critical mass
minimum amount of a nuclide to provide a sustained chain reaction
nuclear fusion
occurs when light-mass nuclei combine to form a heavier, more stable nucleus, produces more energy than fusion and requires very high temperatures
artificial radioactive nuclides
not found in nature and are made through artificial transmutation
artificial transmutation
the bombardment of stable nuclei with charged and uncharged particles
transuranium elements
elements with more than 92 protons in their nuclei
half-life
the time required for half of the atoms of a radioactive nuclide to decay
# of half-lives – time elapsed x (1 half-life/time of half-life) AND THEN….. [A]t x (1/2^n) where n = # of half-lives
how to calculate half-life