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Nuclear Chemistry
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51
Chemistry
11th Grade
02/22/2009

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Term
Nuclear Chemistry
Definition
The branch of chemistry which studies the reactions involving the changes in the nucleus of the atom.
Term
Transmutation
Definition
The change of one element into an entirely different element or elements resulting from a change in the number of protons.
Term
Radioisotopes
Definition
Unstable Isotopes
Term
Radioactivity (radioactive decay)
Definition
The spontaneous uncontrollable breakdown of an unstable atomic nucleus to produce other elements accompanied by the release of particles and rays.
Term
Half Life
Definition
The length of time during which half of a given number of atoms of a radioactive substance decays.
Term
Dosimeter
Definition
A detection device worn by people who work with radiation, uses film exposure to measure the total amount of radiation a person has received.
Term
Radioactive Series
Definition
A chain of transmutations, a chain reaction that will continue until a stable isotope is formed.
Term
Geiger Counter
Definition
Used to detect radiation
Term
Tracer
Definition
When a radioactive isotope is substituted for a stable isotope of the same element. They are used to follow a specific substance as it moves through a natural system.
Term
Radioactive Dating
Definition
The use of half-lives of radioisotopes in determining the age of the earth, ancient relics, and similar objects.
Term
Somatic Injuries
Definition
Biological changes within the body tissue.
Term
Genetic Injuries
Definition
Effect the reproductive cells and can result in hereditary changes.
Term
Fission
Definition
The splitting of a heavy atomic nucleus into two fragments by being bombarded with neutrons.
Term
Breeder Reactor
Definition
Fission reactor that not only produces energy, but manufactures another fuel.
Term
Fusion
Definition
Reactions between two or more light nuclei conbined to form one or more nuclei of less total mass.
Term
How are Matter and Energy Related?
Definition
In nuclear reactions, matter can be converted into energy and energy into matter.
Term
Who discovered radioactivity?
Definition
Henri Becquerel
Term
How was radioactivity discovered?
Definition
Through his interest in the ability of
certain minerals to fluoresce (give off visible light after being exposed to sunlight.), he discovered that
uranium ore gave off invisible rays that penetrate the light proof covering of a photographic plate and
affect the film as if it had been exposed to light rays directly.
Term
What effect did the discovery of radioactivity have on Dalton's indivisible atom?
Definition
It killed the theory.
Term
What caused the fogging of the photographic plates? Who made this discovery?
Definition
The rays emitted by the uranium in the ore "pitch blend" caused the fogging. Discovered by Marie and Pierre Curie.
Term
The Curies discovered which two elements?
Definition
Polonium and Radium
Term
Compare the radioactivity of radium and uranium.
Definition
Radium is 2 million times more radioactive.
Term
State the characteristics of the transuranium elements.
Definition
None occur in nature, radioactive, synthesized, atomic numbers greater than 92.
Term
How are new elements synthesized?
Definition
In nuclear reactors and nuclear accelorators, which accelerate the bombarding particles to very high speeds.
Term
How do radioisotopes gain stability?
Definition
By making changes within their nuclei.
Term
As related to the periodic table, at what point are all the nuclei radioactive?
Definition
All nuclei with an atomic number greater than 83.
Term
What determines the stability of the nucleus?
Definition
The ratio fo protons to neutrons.
1-20= 1:1
Larger= 1:1.5
Term
Label the diagram:
a
X
b
Definition
a= mass number
x=particle or element
b=atomic number or charge
Term
List the three types of radioactive emmision.
Definition
Alpha, Beta, Gamma
Term
What is an alpha particle? What is it's mass and charge?
Definition
4
He
2
It has a mass of 4 atm and positive 2 charge.
Term
Discuss the penetration ability of alpha particles and how they can be stopped.
Definition
Low penetrating ability- can be stopped by a single sheet of paper or even dead cells on the surface of skin.
Term
When are alpha particles dangerous? Explain.
Definition
They are dangerous when ingested- they can penetrate the soft tissue of the body and cause damage.
Term
What is a beta particle? What is the mass and charge of a beta particle?
Definition
0
e
-1
They are electrons. No mass, and a charge of -1.
Term
Discuss the penetration ability of beta particles and how they can be stopped.
Definition
They are almost 100x more penetrating than alpha particles. They can be stopped by a thin sheet of aluminum or thin sheets of wood.
Term
How is the beta particle formed?
Definition
When the nucleus is disrupted, the elements have too many neutrons to become more stable by the breaking apart of a neutron to form a proton and an electron. The electron is shot our as a beta particle.
1 1 0
n ---> p + e
0 1 -1
Term
How does the proton number of an atom change after the release of the beta particle?
Definition
The elements that have too many nuetrons become more stable by the breaking apart of a neutron to form a proton and an electron.
Term
What are gamma rays?
Definition
High energy electromagnetic waves.
Term
Except for their origin, ______ are essentially the same as gamma rays.
Definition
X-rays
Term
What is the mass and charge of gamma radiation?
Definition
It has no mass or charge
Term
Discuss the penetration ability of gamma rays and how they can be stopped.
Definition
They have 1000 times the penetrating ability of alpha. They can be stopped by several meters of concrete or several cm of lead.
Term
What causes gamma radiation to be released? When does this happen?
Definition
Gamma radiation is released, after alpha and beta emission, when the remaining nucleons (protons and neutrons) reorganize into a stable arrangement.
Term
List the properties of the radioactive elements.
Definition
Affect the light sensitive emulsion on photographic film, produce an electrical change in the surrounding air, they produce flourescence with certain other components, undergo radioactive decay.
Term
What is the purpose for adding radium bromine to zinc sulfide?
Definition
It causes the zinc sulfide to glow
Term
State the harmful effects of radiation.
Definition
Can destroy the germinating power of seeds, can kill animals, may cause serious burns, can be fatal.
Term
What isotope is important in radioactive dating?
Definition
Carbon- 14
Term
What instrument is used to follow a tracer throughout a living system?
Definition
A geiger counter
Term
The chemical properties of two isotopes, one stable and one radioactive, are the same. Explain why this is true. How is the radioactivity of an element affected by chemical combination? Explain.
Definition
Chemical properties of an element are determined by the number and arrangement of valence electrons. Isotopes have the same number and arrangement of valence electrons and therefore will have the same chemical properties even if one is radioactive.
Radioactivity is a nuclear property and is determined by the ratio of the protons to the neutrons. Chemical combination involves only the valence electrons and will not change the nucleus of the atom. The radioactivity of an atom is not affected by chemical combination.
Term
List the beneficial uses of radioactivity. Give specific examples.
Definition
Radioactive dating, tracers (medical and industrial), cancer treatment, food preservation, sterilize surgical equipment.
Term
What is the source for the fission reactors?
Definition
U-235
Term
Which type of nuclear reaction is considered the best? Why?
Definition
Fusion- power plants would produce little waste, fuel is obtained from water, releases more energy than fission.
Term
State the disadvantages of both types of nuclear reactions.
Definition
Fission- products are highly radioactive and cannot by discared as ordinary waste, and thermal pollution- the heating of water used as a coolant in some reactors when returned to the environment can kill the existing marine life.

Fusion- very high temperatures are required for a reaction- 40 million degrees K, and a containment vessel that won't melt.
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