Chemistry Unit 4 – Nuclear Chemistry

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The two nuclide symbols
A, X
a nuclear particle
Atomic mass units (AMUS)
1/12 the mass of a carbon 12 atom
mass defect
m in e=mc^2
strong force
Works inside the nucleus, keeps it together
Binding energy
E in E=mc^2, the energy released when a nucleus is formed from separate nucleons
nucelar fission
take 2 small nuclei, put together
Mass number
A = #p+#n
the total number of nucleons
Where did some mass go (mass defect)?
it is converted into energy (E=mc^2)
The mass of one atom is…
slightly less than the sum of its parts
an atom is referred to this in nuclear chemistry
Why is mass lost when combining parts?
The mass defect is caused by the conversion of mass to energy upon formation of the nucleus
Nuclear binding energy
the energy released when a nucleus is formed from nucleons, the amount of energy needed to break apart the nucleus
Band of stability
the stable nuclei cluster over a range of neutron -proton ratios
Nuclear reaction
a reaction that affects the nucleus of an atom
a change in the identity of a nucleus as a result of a change in the number of its protons, one element into another
Radioactive decay
the spontaneous disintegration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation, or both
nuclear radiation
the radiation that exposed the plate, and it is particles or electromagnetic radiation emitted from the nucleus during radioactive decay
alpha particle
two protons and two neutrons bonded together and is emitted from the nucleus during some kinds of radioactive decay
Beta particle
nuclides above stability band are unstable bc their neutron/proton ratio is too large – to decrease neutrons, a neutron can be converted into proton and an electron. The beta particle is an electron emitted from the nucleus during some kids of radioactive decay
high energy electron
beta decay results in increase in atomic number
Nuclides below band of stability- neutron proton ratios too small – must decrease number of protons – proton can be turned into a neutron by emitting a positron. A positron is a particle that has the same mass as an electron, but has a positive charge and is emitted from the nucleus during some kinds of radioactive decay
no mass #
Electron Capture
for nuclides that have a neutron proton ratio that is too small is electron capture – the inner orbital electron is captured by the nucleus (absorbed by nucleus) of its own atom
Inner orbital electron combines with a proton, and a neutron is formed
Gamma rays (emission)
high energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state, nuclear radiation similar to x ray
Half Life
the time required for half the atoms of a radioactive nuclide to decay
Decay series
a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached
Parent Nuclide
The heaviest nuclide of each decay series
Daughter nuclide
the nuclides produces by the decay of the parent nuclide
Artificial transmutations
bombardment of nuclei with charged and uncharged particles
Transuranium elements
elements with more than 92 protons in their nuclei – if #p changes, then element ID changes!
radioactive dating
the process by which the approx age of an object is determined based on the amount of certain radioactive nuclides present
nuclear fission
a very heavy nucleus splits into more stable nucli of intermediate mass
chain reaction
a reaction in which the material that starts the reaction is also one of the products and can start another reaction
Critical mass
the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction – amount of material needed to produce a self-sustaining reaction
radiation-absorbing material that is used to decrease exposure to radiation, espeially gamm rays, from nuclear reactors
control rods
neutron obsorbing rods that help control the reaction by limiting the number of free neutrons
used to slow down the fast neutrons produced by fission
nuclear fusion
low-mass nuclei combine to form a heavier, more stable nucleus
Stability of the nuclei
Depends on the N/Z ratio, for small atoms it should be 1, for large atoms it should be 1.5
Manhatten Project
top secret project to build nuclear fission bombs
Hiroshima bomb
“little boy”, long/skinny, uranium
Nagasaki bomb
“Fat man” bomb, plutonium implosion
Decay constant
nuclear disintigrations per unit time, k
The stability of the nucleus in an atom is determined by
the neutron to proton ratio
What drives the turbine in a nuclear power plant?
The primary fuel for nuclear fusion in the sun and other stars is
The Manhatten project was directed by
Robert Oppenheimer
Categories: Nuclear Chemistry