Nuclear Fission

SCIENCE

RADIOACTIVITY
ELEMENTS

INTRODUCTION

 

This is a list or table of elements that are radioactive. Keep in mind, all elements can have radioactive isotopes. If enough neutrons are added to an atom, it becomes unstable and decays. A good example of this is tritium, a radioactive isotope of hydrogen naturally present at extremely low levels. This table contains the elements that have no stable isotopes. Each element is followed by the most stable known isotope and its half-life.

Note increasing atomic number doesn't necessarily make an atom more unstable. Scientists predict there may be islands of stability in the periodic table, where super heavy transuranium elements may be more stable (although still radioactive) than some lighter elements.

 

 

Element	Most Stable Isotope	Half-life of Most Stable Istope
Technetium	Tc-91	4.21 x 106 years
Promethium	Pm-145	17.4 years
Polonium	Po-209	102 years
Astatine	At-210	8.1 hours
Radon	Rn-222	3.82 days
Francium	Fr-223	22 minutes
Radium	Ra-226	1600 years
Actinium	Ac-227	21.77 years
Thorium	Th-229	7.54 x 104 years
Protactinium	Pa-231	3.28 x 104 years
Uranium	U-236	2.34 x 107 years
Neptunium	Np-237	2.14 x 106 years
Plutonium	Pu-244	8.00 x 107 years
Americium	Am-243	7370 years
Curium	Cm-247	1.56 x 107 years
Berkelium	Bk-247	1380 years
Californium	Cf-251	898 years
Einsteinium	Es-252	471.7 days
Fermium	Fm-257	100.5 days
Mendelevium	Md-258	51.5 days
Nobelium	No-259	58 minutes
Lawrencium	Lr-262	4 hours
Rutherfordium	Rf-265	13 hours
Dubnium	Db-268	32 hours
Seaborgium	Sg-271	2.4 minutes
Bohrium	Bh-267	17 seconds
Hassium	Hs-269	9.7 seconds
Meitnerium	Mt-276	0.72 seconds
Darmstadtium	Ds-281	11.1 seconds
Roentgenium	Rg-281	26 seconds
Copernicium	Cn-285	29 seconds
Nihonium	Nh-284	0.48 seconds
Flerovium	Fl-289	2.65 seconds
Moscovium	Mc-289	87 milliseconds
Livermorium	Lv-293	61 milliseconds
Tennessine	Unknown
Oganesson	Og-294	1.8 milliseconds

 

Formation

Radioactive elements form naturally, as a result of nuclear fission, and via intentional synthesis in nuclear reactors or particle accelerators.

 

Natural

Natural radioisotopes may remain from nucleosynthesis in stars and supernova explosions. Typically these primordial radioisotopes have half-lives so long they are stable for all practical purposes, but when they decay they form what are called secondary radionuclides. For example, primordial isotopes thorium-232, uranium-238, and uranium-235 can decay to form secondary radionuclides of radium and polonium. Carbon-14 is an example of a cosmogenic isotope. This radioactive element is continually formed in the atmosphere due to cosmic radiation.

 

 

Nuclear Fission

Nuclear fission from nuclear power plants and thermonuclear weapons produces radioactive isotopes called fission products. In addition, irradiation of surrounding structures and the nuclear fuel produces isotopes called activation products. A wide range of radioactive elements may result, which is part of why nuclear fallout and nuclear waste are so difficult to deal with.

 

Synthetic

The latest element on the periodic table have not been found in nature. These radioactive elements are produced in nuclear reactors and accelerators. There are different strategies used to form new elements. Sometimes elements are placed within a nuclear reactor, where the neutrons from the reaction react with the specimen to form desired products. Iridium-192 is an example of a radioisotope prepared in this manner. In other cases, particle accelerators bombard a target with energetic particles. An example of a radionuclide produced in an accelerator is fluorine-18. Sometimes a specific isotope is prepared in order to gather its decay product. For example, molybdenum-99 is used to produce technetium-99m.

Commercially Available Radionuclides

Sometimes the longest-lived half-life of a radionuclide is not the most useful or affordable. Certain common isotopes are available even to the general public in small quantities in most countries. Others on this list are available by regulation to professionals in industry, medicine, and science.

 

 

 

 

 

Gamma Emitters

·       Barium-133

·       Cadmium-109

·       Cobalt-57

·       Cobalt-60

·       Europium-152

·       Manganese-54

·       Sodium-22

·       Zinc-65

·       Technetium-99m

Beta Emitters

·       Strontium-90

·       Thallium-204

·       Carbon-14

·       Tritium

Alpha Emitters

·       Polonium-210

·       Uranium-238

Multiple Radiation Emitters

·       Cesium-137

·       Americium-241

 

 

Effects of Radionuclides on Organisms

Radioactivity exists in nature, but radionuclides can cause radioactive contamination and radiation poisoning if find their way into the environment or an organism is over-exposed. The type of potential damage depends on the type and energy of the emitted radiation. Typically, radiation exposure causes burns and cell damage. Radiation can cause cancer, but it might not appear for many years following exposure.

 

Example: