Nuclear Chemistry - New York State Regents
-
Upload
ryan-frank -
Category
Education
-
view
429 -
download
0
Transcript of Nuclear Chemistry - New York State Regents
By R. Frank 2014
NUCLEAR CHEMISTRYNYS REGENTS CHEMISTRY
Radioactivity is the spontaneous disintegration of the nucleus along with the emission of particles and energy.
Nuclear reactions differ from chemical reactions in that the original atoms are changed into atoms of another element. (Photo)
INTRODUCTION TO NUCLEAR CHEMISTRY
Emanations are the particles released when an element disintegrates.
EMANATIONS
Penetration Power is the ability of radiation to pass through matter.
Gamma Particles have the most penetration power, and alpha particles have the least penetration power.
PENETRATING POWER
On the reference tables, elements are radioactive if the atomic masses are in parentheses ( ). For example, elements with an atomic number of over 83 have atomic masses that are all in parentheses, and are therefore radioactive.
IDENTIFYING RADIOACTIVE ELMENTS
Transmutations when one element is changed to another by a change in the nucleus. When an element forms an emanation (Table O), it is a natural transmutation.
An example of a natural transmutation is found below.
NATURAL TRANSMUTATIONS
Artifi cial transmutations occur when a radioactive nuclei is hit with high energy particles, producing neutrons. Examples are fission and fusion.
Fission occurs when heavy nuclei are split to (usually) produce 3 extra neutrons and a lighter nuclei. (Remember, “Fission is Division”)
Fission Reaction:
Fusion occurs when two light nuclei fuse to form a heavier nucleus. (2 small atoms form 1 larger atom)
Fusion Reaction:
ARTIFICIAL TRANSMUTATIONS
1. Which radioactive emanations have a charge of -1?2. Which emanation has the most penetrating power? 3-4. Identify the reactions taking place in the photo
below. Is it fusion, fission, or a natural transmutation. Why?
5. How does a nuclear reaction diff er from a chemical reaction?
6. Is the element Actinium (Ac) a radioactive element? Why or why not? Is Carbon (C) a radioactive element?
MID-UNIT COMPREHENSION CHECK
Stability of an element is dependent on its ratio of protons to neutrons. An element is stable when this ratio is close to 1:1.
A half-life is the time it takes for half the atoms of a radioactive nuclide to decay. The shorter the half-life, the less stable it is.
HALF-LIFE
Fissionable fuels power the reactor and include U-233, U-235, and Pu-239.
Moderators decrease the speed of neutrons, and can be heavy water, water, beryllium, or graphite.
Control rods absorb extra neutrons, and can be baron or cadmium.
Coolants keep the temperature of the reactors cool. They include water, heavy water, helium, carbon dioxide or molten lithium and sodium
NUCLEAR REACTORS
NUCLEAR REACTORS
Fissionable FuelsFissionable
Fuels
Control Rods
Coolants
Shielding prevents radiation leakage. External – High-density concrete. (Shown) Internal – Steel.
SHIELDING
Solid and liquid radioactive wastes are encased and stored underground.
Radioactive gases are stored until they can be safely released into the environment.
DISPOSING OF RADIOACTIVE WASTE
Tracers are radioactive isotopes used to follow the course of a chemical reaction.
IODINE-131 is used for thyroid disorders.
CARBON-14 is used for carbon dating of organic materials, living things, and photosynthetic reactions.
URANIUM-238 and LEAD(Pb)-206 are used for geologic dating.
TECHNICIUM (Tc) -99 is used for brain tumors.
RADON-226 and COBALT-60 are used for cancer treatments because they kill living cells.
RADIOACTIVE TRACERS
Radiation is used to preserve food.
Radiation is used in medicine because of its short half-life and quick elimination.
PRACTICAL USES OF RADIOACTIVITY
R. Frank 2014