Radioactivity Flashcards
March 1, 1896: Discovers Radioactivity (American Physical Society, 2008)
Henri Becquerel
is the ability of a crystal to absorb light and reemit light sometime after the exciting light has been removed.
Phosphorescence
Becquerel reported at the French Academy of Science meeting on ________ that the phosphorescent uranium salts absorbed sunlight and emitted a penetrating radiation similar to x-rays.
February 24, 1896
In 1898, They figured out how to measure the intensity of the radioactivity, and soon found other radioactive elements: polonium, thorium and radium.
Marie and Pierre Curie
Concepts of radioactivity that the atoms of the substance spontaneously emit invisible but energetic radiations, which can penetrate materials that are opaque to visible light
(Lawson, 1999)
will change one nucleus to another if the product nucleus has a greater nuclear binding energy than the initial decaying nucleus.
Radioactive decay
is the energy required to separate an atomic nucleus completely into its constituent protons and neutrons
Nuclear binding energy
Nuclei with an excess of protons or neutrons in comparison with the stable nuclei will decay toward the stable nuclei by changing protons into neutrons or neutrons into protons, or else by shedding neutrons or protons ________
Combination
The positive charges of the protons tend to force the protons apart _______
Electromagnetic Force
It governs how an unstable nucleus will decay into a stable nucleus. It is responsible for the disintegration in matter.
Weak Force
A plot of the number of neutrons versus the number of protons for stable nuclei reveals that the stable isotopes fall into a narrow band. This region is known as the band of stability
Belt of Stability
It is a property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously.
Radioactivity
It is a property of several naturally occurring elements as well as of artificially produced isotopes of the elements.
Radioactive decay
These include long-lived radioactive elements such as uranium, thorium, and any of their decay products, such as radium and radon
Terrestrial Sources
• These include nuclear explosives, radioactive fallout from Nuclear Weapon Testing, nuclear reactors, waste from the processing of reactor fuel elements and others
Artificial Sources
Also known as decay rate. This refers to the number of times a radioactive decay occurs in the sample per unit time.
Activity
It is the activity per unit mass of a substance, whether atoms of a single nuclide or a compound
Specific Activity
the amount of time it takes for the decay rate (or count rate) to reach half of its original value
Half-life t1/2
life is the amount of time it takes for a given isotope to lose half of its radioactivity
Half-life
A type of half-life is defined as the period of time required to reduce the radioactivity level of a source to exactly one half its original value due solely to radioactive decay.
Physical Half-life
Is defined as the period of time required to reduce the amount of a drug/pharmaceutical in an organ or the body to exactly one half its original value due solely to biological elimination.
Biological Half-life
is defined as the period of time required to reduce the radioactivity level of an internal organ or of the whole body to exactly one half its original value due to both elimination and decay.
Effective Half-life
It states that “the probability per unit time that a nucleus will decay is a constant, independent of time.”
Radioactive Decay Law
