Glossary of Nuclear Chemistry 2
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- -poses little health hazard
-low penetration, stopped by paper
- -can damage skin (1-2 mm)
- medium, stopped by heav clothing
- -very hazardous to health, damages tissues
-high, stopped by lead
- protons and neutrons located in the nucleus of the atom
- an atom identified by the number of protons and neutrons in its nucleus
- Mass Defect
- -difference between the mass of an atom and the sum of the masses of its protons, neutrons, electrons
-caused by conversion of msas to energy upon formation of nucleus. E=mc squared
- Nuclear Binding Energy
- energy released when a nucleus is formed from nucleons (amount of energy required to break apart the nucleus)
The higher the binding energy, the more stable the nucleus
Binding energy per nucleon is the binding energy of the nucleus divided by the number of nucleons it contains
- Band of Stability
- most stable nuclei are those with a proton-neutron ratio of approx. 1:1
Stable Nuclides tend to have even numbers of nucleons
No stable nuclides beyond 83/ Those higher than 92 aren't in nature
- Nuclear Forces
- short range pn,pp,nn: hold the nuclear particles together in the nucleus
When he number of prtons increase, more neutrons are needed to stabilize the increased repulsive forces
- protons repel protons except in the nucleus
same with protons, and protons/neutrons
- Nuclear Reaction
- reaction which affects the nucleus of an atom
- change in the identity of a nucleus as a result of a change in the number of its protons
- Radioactive decay
- spontaneous disinteggration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation or both.
Radioactive atoms: radioactive nuclides- unstable nuclei that decay
- Half Life
- the time required for half the atoms of a radioactive nuclide to decay
- Decay Series
- series of radioactive nuclides produced by successive radioactive decay until a stable uclide is reached. Heaviest nuclide of each decay series is the parent nuclide. Nuclides produced by the decay of the parent nuclides are called the daughter nuclides.
All nuclides with atomic numbers greater than 83 are radioactive and belon to one of three natural decay series.
U-238, U-235, Thorium-232
- Artificial Transmutation
- bombardment of the nuclei with charged an duncharged particles: process used to make artificial radioactice nuclides
- Transuranium elements
- elements with more than 92 protons
- Nuclear Fission
- a very heavy nucleus splits into more stable nuclei of intermediate mass
Fission releases enormous amounts of energy. Nuclear fission can occur spontaneously or when nuclei are bombarded with particles.
Fission of an atom bombarded by neutrons produces more neutrons- a chain raction occurs
- 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
- minimum amount of nuclides that provides the number of netrons needed to sustain a chain reaction.
If mass of fuel is below certain minimum, too many neutrons escape without strikig other nuclei and chain reaction will stop.
- Nuclear Fusion
- low mass nuclei combine to form a heavier, more stable nucles.
- unit to measure nuclear radiation exposure.
- unit used to measure the does of any type of ionizing radiation that factors in the effect that the radiation has on human tissue
- Geiger-Muller counters/film badges
- film badges: exposure of film
count electric pulses carried by gas ionized by radiation
- Scintillation counters
- instruments that convert scintillating light to an electric signal for detecting radiation (radiation can be detected when it transfers its energy to substances that absorbs ionizing radiation and emit visible light
- Radioactive Dating
- process by which the approximate age of an object is determined based on the amount of certain radioactice nuclides present
Carbon-14 is radioactive and has a half life 5715 years. It can be used to date organic material up to 50,000 years old. Nuclides with longer half lives are used to estimate older objects.
- Radioactive Nuclides in Medicine
- 1. can be used to destroy cancer cells
2. radioactive tracers that are incorporated into substances so that movement of the substances can be followed by radiation detectors.
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