Review Article - (2017) Volume 5, Issue 6
Isotopes were discovered by Frederick Soddy which are the different forms of the same elements that differs in their number of neutrons and also possess radioactive properties. These isotopes are relatively stable and could be used for numerous purposes.
Keywords: Neutrons; Radioactive; Atomic number; Atomic mass
Discovery of isotopes began when evidences were gathered to reveal that some element possess radioactive properties. In 1910, it was observed that certain elements transformed from their unstable state to a highly stable state following the emission of radiations that were found to be radioactive. Salts of thorium and uranium were identified as radioactive. Ionium was produced by uranium ores while mesothorium was yielded by thorium ores which gave these elements their recognized names. Since ionium when mixed with thorium could not be restored by chemicals routes. Likewise, mesothorium was found to be chemically similar to radium. So, it was concluded that ionium and mesothorium were different forms of their corresponding existing elements. Such elements were termed as “Isotopes” by Frederick Soddy who won a Nobel Prize in 1921 for his tremendous work [1]. Isotope is defined as the form of the same elements with different number of neutrons. It means they differs in their atomic masses but have similar atomic number therefore occupy the same position in the periodic table. He also revealed uranium and thorium decay into different isotopes of lead. Since lead was discovered from uranium and thorium rich ores with different atomic masses of 206.08 and 207.69 respectively [2-4]. There are numerous stable isotopes of different element with varying relative abundance given below in Table 1 [5-9].
| Isotope | Rel.Abundance | Half-life (years) |
|---|---|---|
| Holmium-166m | - | 1,200 |
| Berkelium-247 | - | 1,380 |
| Radium-226 | Trace | 1,600 |
| Molybdenum-93 | - | 4,000 |
| Holmium-153 | - | 4,570 |
| Curium-246 | - | 4,730 |
| Carbon-14 | Trace | 5,730 |
| Plutonium-240 | - | 6,563 |
| Thorium-229 | - | 7,340 |
| Americium-243 | - | 7,370 |
| Curium-245 | - | 8,500 |
| Curium-250 | - | 9,000 |
| Tin-126 | - | 10,000 |
| Iodine-129 | - | 15,700 |
| Niobium-94 | - | 20,300 |
| Plutonium-239 | - | 24,110 |
| Proactinium-231 | Trace | 32,760 |
| Lead-202 | - | 52,500 |
| Lanthanium-137 | - | 60,000 |
| Thorium-230 | - | 75,380 |
| Nickel-59 | - | 76,000 |
| Thorium-230 | Trace | 77,000 |
| Calcium-41 | - | 103,000 |
| Neptunium-236 | - | 154,000 |
| Uranium-233 | - | 159,200 |
| Rhenium-186m | - | 200,000 |
| Technetium-99 | - | 211,000 |
| Krypton-81 | - | 229,000 |
| Uranium-234 | Trace | 245,500 |
| Chlorine-36 | - | 301,000 |
| Curium-248 | - | 340,000 |
| Bismuth-208 | - | 368,000 |
| Plutonium-242 | - | 373,300 |
| Aluminum-26 | - | 717,000 |
| Selenium-79 | - | 1,130,000 |
| Iron-60 | - | 1,500,000 |
| Beryllium-10 | - | 1,510,000 |
| Zircon-93 | - | 1,530,000 |
| Curium-247 | - | 1,560,000 |
| Gadolinium-150 | - | 1,790,000 |
| Neptunium-237 | - | 2,144,000 |
| Cesium-135 | - | 2,300,000 |
| Technetium-96 | - | 2,600,000 |
| Dysprosium-154 | - | 3,000,000 |
| Bismuth-310m | - | 3,040,000 |
| Mietnerium-53 | - | 3,740,000 |
| Technetium-98 | - | 4,200,000 |
| Lead-205 | - | 15,300,000 |
| Hafnium-182 | - | 9,000,000 |
| Palladium-107 | - | 6,500,000 |
| Curium-247 | Abundant | 15,600,000 |
| Uranium-236 | - | 23,420,000 |
| Niobium-92 | - | 34,700,000 |
| Plutonium-244 | - | 80,800,000 |
| Samarium-146 | - | 103,000,000 |
| Uranium-236 | - | 234,200,000 |
| Uranium-235 | Rare | 703,800,000 |
| Potassium-40 | Rare | 1,280,000,000 |
| Uranium-238 | Abundant | 4,468,000,000 |
| Rubidium-87 | Abundant | 4,750,000,000 |
| Thorium-232 | Abundant | 14,100,000,000 |
| Lutetium-176 | Rare | 37,800,000,000 |
| Rhenium-187 | Abundant | 43,500,000,000 |
| Lanthanium-138 | Rare | 105,000,000,000 |
| Samarium-147 | Abundant | 106,000,000,000 |
| Platinum-190 | Rare | 650,000,000,000 |
| Tellurium-123 | Rare | >1 × 1013 |
| Osmium-184 | Rare | >5.6 ×1013 |
| Gadolinium-152 | Rare | 1.08 × 1014 |
| Tantalum-180m | Rare | >1.2 × 1015 |
| Xenon-124 | Rare | >1.6 ×1014 |
| Indium-115 | Abundant | 4.41 × 1014 |
| Zinc-70 | Rare | >5 × 1014 |
| Hafnium-174 | Rare | 2.0 ×1015 |
| Osmium-186 | Abundant | 2.0 × 1015 |
| Samarium-149 | Abundant | >2 × 1015 |
| Neodymium-144 | Abundant | 2.29 × 1015 |
| Samarium-148 | Abundant | 7 × 1015 |
| Cadmium-113 | Abundant | 7.7 × 1015 |
| Cerium-142 | Abundant | >5 × 1016 |
| Tungsten-183 | Abundant | >1.1 × 1017 |
| Vanadium-50 | Rare | 1.4 × 1017 |
| Lead-204 | Abundant | 1.4 × 1017 |
| Chromium-50 | Abundant | >1.8 × 1017 |
| Tungsten-184 | Abundant | >3 × 1017 |
| Calcium-48 | Abundant | >6.3 × 1018 |
| Molybdenum-100 | Abundant | 1.0 × 1019 |
| Neodynium-150 | Abundant | >1.1 × 1019 |
| Zircon-96 | Abundant | >3.8 × 1019 |
| Selenium-82 | Abundant | 1.1 × 1020 |
| Tellurium-130 | Abundant | 7.9 × 1020 |
| Xenon-136 | Abundant | >2.4 × 1021 |
| Tellurium-128 | Abundant | 2.2 × 1024 |
Table 1: List of Isotopes.
These stable isotopes of different elements have a wide range of applications in different research areas some of their applications are stated below in Table 2 [10-20].
| Isotopes | Uses |
|---|---|
| Thorium-230 | Coloring and fluorescent agent in glassware and colored glazes |
| Californium-252 | Explosives detection, monitor soil moisture content and the moisture of materials stored in soils |
| Krypton-85 | Monitors thickness of thin plastics, metal sheet, rubber, textiles and paper. Pollutant indicator. Used in indicator lights in different electronic appliances. |
| Carbon-14 | Biological tracer for pharmacological studies. |
| Cesium-137 | Chemotherapy of cancers and tumors, measurement of correct radiomedicine, monitoring and controlling fluid flow in pipelines etc. |
| Americum-241 | smoke detectors, measure levels of toxic lead in dried paint samples |
| Tritium (H3) | Geological mining, hydrology, used in luminous paint |
| Iron-55 | Electroplating solutions analysis, detection of sulphur in air, metabolic pathway studies. |
| Cobalt-60 | Surgical instruments sterilization, cancer treatment, food irradiation and radiography. |
| Thoriated Tungsten | Used in welding, aircraft, petrochemical and food processing equipment industries. |
| Uranium-235 | Nuclear fuel for power plants and naval nuclear propulsion |
| Cadmium-109 | Analyzing metal alloys, scrap sorting |
| Sodium-24 | Detection of oil leakages in industrial pipelines |
| Plutonium-238 | Has powered more than 20 NASA spacecrafts since 1972 |
| Nickel-63 | Explosives detection, voltage regulators, current flow protectors in electronic devices. |
| Thallium-204 | Detect and quantifies pollutant levels and measures the thickness of plastics, sheet metal, rubber, textiles, and paper. |
| Promethium-147 | Used in electric blanket thermostats |
| Sulphur-35 | Used in survey meters in case of emergencies |
| Curium-244 | Geological mining to analyze material unearthed from pits and slurries from drilling operations |
| Polonium-210 | Reduction of static charge in production of photographic film |
| Sulphur-35 | Used in survey, cigarette manufacturing sensors and medical therapies. |
| Iridium-192 | Used to test the integrity of pipeline welds, boilers and aircraft parts and in brachy therapy/tumor irradiation. |
| Radium-226 | Makes lighting rods more effective. |
| Thorium-230 | Used as coloring and fluorescence agents |
Table 2: Applications of Isotopes.
Suppliers of radioisotopes
The main world isotope suppliers are as follows:
ANSTO in Australia,
BR-2 at Mol in Belgium,
Dimitrovgrad in Russia,
ETRR-2 in Egypt,
FRJ-2/ FRM-2 at Julich in Germany,
HFETR at Chengdu in China,
HFR at Petten in Netherlands,
IRE in Europe,
Isotope-NIIAR in Russia,
LWR-15 at Rez in Czech Republic,
Mallinckrodt Pharmaceuticals in Ireland,
Maria in Poland,
MDS Nordion in Canada,
NRU at Chalk River in Canada,
NTP in South Africa,
OPAL in Australia
Osiris & Orphee at Saclay in France,
So, it was concluded that discovery of different isotopes of different elements could offer numerous biological and chemical applications used for the welfare of mankind.
