Isotopes

Isotopes are different forms of the same element that have the same number of protons but a different number of neutrons in their atomic nuclei. This difference in neutron count leads to variations in atomic mass, but the chemical properties of the isotopes remain largely similar because they have the same electron configuration.

Environmental isotopes are variants of chemical elements that contain the same number of protons but differ in the number of neutrons, resulting in different atomic masses. These isotopes can serve as important tools in environmental science, ecology, geochemistry, and other fields, as they can provide valuable information about various environmental processes, historical climate conditions, and the movement of water and other substances in the environment. Isotopes can be stable or unstable (radioactive).

Carbon-13 (C-13) is a stable isotope of carbon, which has an atomic mass of approximately 13 atomic mass units (amu). It consists of six protons and seven neutrons in its nucleus, distinguishing it from the more common carbon isotope, Carbon-12 (C-12), which has six protons and six neutrons. Carbon-13 makes up about 1.1% of all naturally occurring carbon in the environment.

Carbon-14 (C-14) is a radioactive isotope of carbon. It is formed in the upper atmosphere when cosmic rays interact with nitrogen-14 (N-14) in a process known as cosmic ray spallation. Carbon-14 has a half-life of about 5,730 years, which means that it takes this amount of time for half of a given sample of C-14 to decay into nitrogen-14 through beta decay.

Chlorine-36 (\(^{36}\text{Cl}\)) is a stable isotope of chlorine, which is a chemical element with the symbol Cl and atomic number 17.

Deuterium is a stable isotope of hydrogen, represented by the symbol \( \text{D} \) or \( ^2\text{H} \). It contains one proton and one neutron in its nucleus, giving it a mass number of 2, compared to the more common hydrogen isotope, protium, which has no neutrons. Deuterium occurs naturally in small amounts in water, comprising about 0.0156% of all hydrogen in the ocean.

Environmental radioactivity refers to the presence and concentration of radioactive materials in the environment, including air, water, soil, and living organisms. This radioactivity is a natural phenomenon resulting from the decay of radioactive isotopes that are found in the earth's crust, cosmic radiation from outer space, and human-made sources. **Sources of Environmental Radioactivity:** 1. **Natural Sources:** - **Cosmic Rays:** High-energy particles from outer space that contribute to background radiation.

Extinct isotopes of superheavy elements refer to isotopes of elements that lie beyond the currently known periodic table. Superheavy elements are those with atomic numbers greater than 103 (lawrencium) and are typically synthesized in laboratories through nuclear reactions. These elements are often highly unstable, with very short half-lives, leading them to decay rapidly into lighter elements.

Oxygen-17 (³¹₆O) is a stable isotope of oxygen. It contains 8 neutrons and 9 protons in its nucleus, giving it a mass number of 17. In naturally occurring oxygen, about 0.037% is this isotope, making it relatively rare compared to the more common isotopes, Oxygen-16 (the most abundant) and Oxygen-18.

Oxygen-18 (⁴O) is a stable isotope of oxygen that is characterized by having 8 protons and 10 neutrons in its nucleus. It is one of three naturally occurring isotopes of oxygen, the others being Oxygen-16 (⁴O) and Oxygen-17 (⁴O). Oxygen-18 is less abundant than Oxygen-16, making up about 0.2% of naturally occurring oxygen.

Tritium is a radioactive isotope of hydrogen, denoted as \( ^3H \) or T. It contains one proton and two neutrons in its nucleus, making it heavier than the most common hydrogen isotope, protium (\( ^1H \)), which has only one proton and no neutrons. Tritium is produced naturally in the atmosphere through interactions between cosmic rays and nitrogen.

Δ¹³C (delta carbon-13) is a measure used in the field of stable isotope geochemistry to express the ratio of carbon isotopes, specifically the stable isotopes carbon-12 (¹²C) and carbon-13 (¹³C). The delta notation is used to give the relative difference in the isotopic composition of a sample compared to a standard reference material.

Δ¹⁸O (Delta oxygen-18) is a measure of the ratio of stable isotopes of oxygen, specifically the ratio of oxygen-18 (¹⁸O) to oxygen-16 (¹⁶O). It is expressed as a difference in parts per thousand (‰) compared to a standard reference material, typically Vienna Standard Mean Ocean Water (VSMOW).

Δ⁻⁴S (delta sulfur-34) is a notation used in geochemistry and environmental science to express the isotopic composition of sulfur in a sample relative to a standard. Specifically, it refers to the ratio of sulfur-34 (¹⁴S) to sulfur-32 (¹³²S) isotopes.

Actinium (Ac) has several isotopes, with the most notable being Actinium-227 and Actinium-228. Here are some details about its isotopes: 1. **Actinium-227 (Ac-227)**: - Half-life: About 21.77 years. - Decay mode: It decays to radium-223 via alpha decay.

Actinium-225 (Ac-225) is a radioactive isotope of the element actinium, which is part of the actinide series in the periodic table. It has a half-life of approximately 10 days, making it a relatively short-lived isotope. Ac-225 is important in the field of nuclear medicine, particularly in targeted alpha-particle therapy (TAT), which is a form of cancer treatment.

Aluminium has several isotopes, but the most notable and stable isotopes are: 1. **Aluminium-26 (\(^26\text{Al}\))**: This is a radioactive isotope with a half-life of about 730,000 years. It is produced through cosmic ray interactions and is significant in astrophysical studies and in dating geological formations.

Aluminium-26 (often written as \(^{26}\text{Al}\)) is a radioactive isotope of aluminium. It has a nucleon count of 26, consisting of 13 protons and 13 neutrons. \(^{26}\text{Al}\) is notable for its half-life of about 717,000 years, which allows it to be used in various scientific studies.

Americium (Am) is a synthetic element with the atomic number 95, and it has several isotopes. The most significant isotopes of americium are: 1. **Americium-241 (Am-241)**: This is the most commonly used isotope of americium. It has a half-life of about 432.2 years and is used in smoke detectors, certain types of radiation sources, and in some industrial applications.

Americium-241 (Am-241) is a radioactive isotope of the element americium, which is part of the actinide series in the periodic table. Americium is a synthetic element, first produced in 1944 by Glenn T. Seaborg and his team at the University of California, Berkeley. Am-241 has a half-life of approximately 432.2 years, meaning it takes that amount of time for half of a sample of this isotope to decay.

Antimony (Sb) has several isotopes, but the most notable ones are: 1. **\(^{121}\text{Sb}\)**: This is the most stable and abundant isotope of antimony, accounting for about 57% of natural antimony. It has a half-life that is effectively stable as it doesn't undergo radioactive decay. 2. **\(^{123}\text{Sb}\)**: This isotope makes up about 42% of natural antimony and is also stable.

Argon has several isotopes, but the most common ones are: 1. **Argon-36** (¹⁶Ar) - This is a stable isotope and constitutes about 0.34% of natural argon. 2. **Argon-38** (³⁸Ar) - Another stable isotope, making up about 0.06% of natural argon.

Arsenic has several isotopes, with the most notable being: 1. **Arsenic-75 (As-75)**: This is the only stable isotope of arsenic and is the most abundant, making up about 100% of naturally occurring arsenic. 2. **Radioactive Isotopes**: Arsenic has several radioactive isotopes, which are not stable and decay over time.

Astatine is a radioactive element with the atomic number 85. It has several isotopes, most of which are unstable. The known isotopes of astatine range from Astatine-210 to Astatine-218, and they are primarily categorized by their mass numbers. The most significant isotopes include: 1. **Astatine-210 (At-210)**: This isotope has a half-life of about 8.

Barium has several isotopes, which are variants of the element that have the same number of protons but different numbers of neutrons. The most stable and common isotopes of barium are: 1. **Barium-130 (Ba-130)**: This is the most abundant isotope, comprising about 7.1% of natural barium. 2. **Barium-132 (Ba-132)**: This isotope is also stable and is about 0.

Berkelium (Bk) is a synthetic element with atomic number 97 and is part of the actinide series. It has several isotopes, the most notable of which are: 1. **Berkelium-247 (Bk-247)**: This is the most stable and commonly referenced isotope of berkelium, with a half-life of approximately 1,380 days (about 3.8 years).

Beryllium has several isotopes, but the most significant ones are: 1. **Beryllium-7 (Be-7)**: This isotope has a mass number of 7 and is a radioactive isotope with a half-life of about 53.1 days. It is produced in the atmosphere through the interaction of cosmic rays with nitrogen and oxygen. Beryllium-7 decays by beta decay into lithium-7.

Beryllium-10 (\(^10\text{Be}\)) is a radioactive isotope of beryllium, which is a chemical element with the symbol Be and atomic number 4. \(^10\text{Be}\) is formed in the atmosphere as a result of cosmic ray interactions with oxygen and nitrogen, and it can also be produced through various nuclear reactions.

Bismuth (Bi) has several isotopes, but the most notable ones are: 1. **Bismuth-209 (Bi-209)**: This is the most stable and abundant isotope of bismuth, constituting nearly 100% of natural bismuth. It has a half-life of about 1.9 x 10^19 years, making it effectively stable for practical purposes.

Bismuth-209 is an isotope of the element bismuth, which has the chemical symbol Bi and an atomic number of 83. Bismuth-209 is notable because it is the most stable isotope of bismuth, with a half-life of about 1.9 × 10^19 years, making it extremely long-lived compared to other isotopes of bismuth.

Bohrium (Bh) is a synthetic element with the atomic number 107. It was first synthesized in 1981 and is named after the physicist Niels Bohr. Currently, several isotopes of bohrium have been produced, but they are all radioactive and have relatively short half-lives. The most notable isotopes of bohrium include: 1. **Bohrium-262 (Bh-262)**: This isotope has a half-life of about 5.6 milliseconds.

Boron has two stable isotopes and several unstable isotopes. The two stable isotopes of boron are: 1. **Boron-10 (¹⁰B)**: This isotope has 5 protons and 5 neutrons, and it constitutes about 19.9% of naturally occurring boron. It is often used in applications such as neutron capture therapy for treating cancer and in various nuclear applications.

Bromine has several isotopes, but the two most notable ones are: 1. **Bromine-79 (Br-79)**: This is the most stable and abundant isotope of bromine, making up about 50.5% of naturally occurring bromine. It has a half-life that is stable (not radioactive), and it consists of 35 protons and 44 neutrons.

Cadmium (Cd) has several isotopes, with the most stable and common ones being: 1. **Cadmium-106 (Cd-106)**: This isotope is stable and has a natural abundance of about 1.25%. 2. **Cadmium-108 (Cd-108)**: Also stable, this isotope has an abundance of about 0.89%. 3. **Cadmium-110 (Cd-110)**: Another stable isotope, it comprises roughly 12.

Caesium (Cs) has several isotopes, with the most stable and commonly known ones being: 1. **Cs-133**: This is the most stable isotope of caesium and is used as the standard for the definition of the second in the International System of Units (SI). Cs-133 has a half-life of stable, meaning it does not undergo radioactive decay.

Caesium-137 (Cs-137) is a radioactive isotope of the element cesium. It has a half-life of about 30.1 years and is produced as a byproduct of nuclear fission in reactors and during the decay of certain isotopes, such as in the fallout from nuclear weapons testing or nuclear accidents. Cs-137 emits beta particles and gamma radiation, making it a source of ionizing radiation.

Calcium has several isotopes, which are variants of the element that have the same number of protons but different numbers of neutrons. The isotopes of calcium are: 1. **Calcium-40 (⁴⁰Ca)** - The most abundant and stable isotope, making up about 97% of naturally occurring calcium. It has 20 protons and 20 neutrons.

Calcium-48 (\(^{48}\text{Ca}\)) is an isotope of the element calcium, which has the atomic number 20. This specific isotope has 20 protons and 28 neutrons, giving it a mass number of 48. Calcium-48 is one of the most stable isotopes of calcium, with a very long half-life, and it is of particular interest in nuclear physics and astrophysics due to its unique properties.

Californium (Cf) has several isotopes, of which the most notable are: 1. **Californium-252 (Cf-252)**: This isotope is one of the most prominent, with a half-life of about 2.645 years. It is a powerful neutron emitter and is used in various applications, including neutron radiography, chemotherapy, and as a neutron source in scientific research.

Carbon has three main isotopes: carbon-12 (\(^{12}\text{C}\)), carbon-13 (\(^{13}\text{C}\)), and carbon-14 (\(^{14}\text{C}\)). Each isotope has the same number of protons but a different number of neutrons, leading to differences in their atomic masses.

Carbon-12 (\(^12C\)) is a stable isotope of carbon, which is one of the fundamental elements in chemistry and biology. It is the most abundant carbon isotope, accounting for about 98.9% of all naturally occurring carbon.

Fractionation of carbon isotopes in oxygenic photosynthesis refers to the differential uptake and incorporation of carbon isotopes (\(^{12}C\) and \(^{13}C\)) by photosynthetic organisms, primarily plants and cyanobacteria, during the process of converting carbon dioxide (CO2) into organic carbon compounds using sunlight.

Isotopically pure diamond refers to a diamond that is composed entirely of one stable isotope of carbon, typically carbon-12 (C-12). Natural diamonds contain a mixture of carbon isotopes, mainly carbon-12 and carbon-13, with trace amounts of carbon-14 present due to cosmic radiation.

Cerium (Ce) is a chemical element with atomic number 58 and belongs to the lanthanide series. It has several isotopes, which are variants of the element with the same number of protons but a different number of neutrons. The isotopes of cerium are: 1. **^136Ce** - Stable isotope with 78 neutrons. 2. **^138Ce** - Stable isotope with 80 neutrons.

Chlorine has two stable isotopes, which are: 1. **Chlorine-35 (¹⁷Cl)**: This isotope has 17 neutrons and is the more abundant of the two, making up about 76% of naturally occurring chlorine. 2. **Chlorine-37 (¹⁹Cl)**: This isotope has 20 neutrons and accounts for about 24% of natural chlorine.

Chlorine-37 (\(^{37}\text{Cl}\)) is an isotope of chlorine, which is a chemical element with the symbol Cl and atomic number 17. It has a nuclear mass number of 37, meaning it contains 17 protons (which is characteristic of all chlorine atoms) and 20 neutrons (since 37 - 17 = 20).

Chromium has several isotopes, which are variants of the element with the same number of protons but different numbers of neutrons. The most notable isotopes of chromium are: 1. **Chromium-50 (⁵⁰Cr)**: This is the most abundant isotope, making up about 4.3% of natural chromium. It has 24 protons and 26 neutrons.

Cobalt has several isotopes, but the most notable ones are: 1. **Cobalt-59 (^59Co)** - This is the only stable isotope of cobalt, making up nearly 100% of naturally occurring cobalt. It has 27 protons and 32 neutrons. 2. **Cobalt-60 (^60Co)** - This is a radioactive isotope with a half-life of about 5.27 years.

Cobalt-60 is a radioactive isotope of cobalt, denoted as \(^{60}\text{Co}\). It has important applications in various fields, particularly in medicine and industry. Here are some key points about Cobalt-60: 1. **Radioactive Properties**: Cobalt-60 undergoes beta decay to become nickel-60, emitting gamma radiation in the process. Its half-life is approximately 5.

Copernicium (Cn) is a synthetic element with the atomic number 112. It is a member of the group 10 elements in the periodic table. As of now, there are currently a few known isotopes of copernicium, but all are highly unstable and radioactive. The most notable isotopes of copernicium include: 1. **Copernicium-277 (\(^{277}\)Cn)**: This isotope has a half-life of about 0.

Copper has two stable isotopes: \( ^{63}Cu \) and \( ^{65}Cu \). 1. **\( ^{63}Cu \)**: This isotope has 29 protons and 34 neutrons, comprising about 69% of naturally occurring copper. Its atomic mass is approximately 62.93 u.

Copper-64 (^64Cu) is a radioactive isotope of copper. It has a total of 29 protons and 35 neutrons in its nucleus. Copper-64 is notable for its applications in both nuclear medicine and scientific research. ### Key Characteristics: - **Half-life**: The half-life of Copper-64 is approximately 12.7 hours, which makes it suitable for certain medical applications where a shorter-lived isotope is beneficial.

Curium (Cm) is an actinide element with atomic number 96. It has several isotopes, with the most notable being: 1. **Curium-242 (Cm-242)**: This is the most stable isotope of curium and has a half-life of about 162.8 days. It decays primarily by alpha emission. 2. **Curium-244 (Cm-244)**: This isotope has a half-life of approximately 18.

Darmstadtium is a synthetic element with the symbol Ds and atomic number 110. It is part of the transactinide series of elements and was first synthesized in 1994. As of now, darmstadtium has no stable isotopes; all of its isotopes are radioactive.

Dubnium (Db) is a synthetic element with the atomic number 105. It has several known isotopes, most of which are highly radioactive and have relatively short half-lives. The most studied isotopes of dubnium include: 1. **Dubnium-263 (Db-263)**: This is the most stable isotope of dubnium, with a half-life of about 34 seconds. It decays primarily through alpha decay.

Dysprosium has several isotopes, but the most notable ones are: 1. **Dysprosium-156 (Dy-156)**: This is the most abundant stable isotope of dysprosium, making up about 5.3% of natural dysprosium. 2. **Dysprosium-158 (Dy-158)**: Another stable isotope, it accounts for approximately 0.1% of natural dysprosium.

Einsteinium (Es) is a synthetic element with the atomic number 99. It has several isotopes, the most notable of which are: 1. **Einsteinium-253 (Es-253)**: This is the most stable isotope of einsteinium, with a half-life of about 20.5 days. It is produced in nuclear reactors and is used in research.

Erbium (Er) has several isotopes, with the most stable and common isotopes being: 1. **Erbium-162 (Er-162)**: This is the most abundant stable isotope, comprising about 33.5% of natural erbium. 2. **Erbium-164 (Er-164)**: This is another stable isotope, making up about 1.6% of natural erbium.

Europium (Eu) has a number of isotopes, but the most significant ones are Europium-151 and Europium-153, which are the only naturally occurring isotopes. 1. **Europium-151 (Eu-151)**: This isotope has an atomic mass of approximately 150.9198 u and has a natural abundance of about 47.8%. It is stable and does not undergo radioactive decay.

Fermium (Fm) is a synthetic element with the atomic number 100. It is part of the actinide series in the periodic table. Isotopes of fermium are all radioactive, as fermium has no stable isotopes. The most notable isotopes of fermium include: 1. **Fermium-257 (Fm-257)**: This is the most stable isotope of fermium, with a half-life of about 100.5 days.

Flerovium (Fl) is a synthetic element with atomic number 114, and it is part of the superheavy elements in the periodic table. As of my last knowledge update in October 2023, there are very few known isotopes of flerovium, primarily because it is extremely unstable and has a short half-life.

Fluorine has one stable isotope, which is fluorine-19 (¹⁹F). This isotope accounts for nearly all naturally occurring fluorine. Fluorine-19 has 9 protons and 10 neutrons in its nucleus. In addition to the stable isotope, fluorine has several radioactive isotopes, though they are not found in significant amounts in nature.

Fluorine-18 is a radioactive isotope of fluorine, which is a chemical element with the symbol F and atomic number 9. Fluorine-18 has a mass number of 18, indicating it has 9 protons and 9 neutrons in its nucleus. This isotope is notable for its applications in positron emission tomography (PET), a medical imaging technique. Fluorine-18 is produced in a cyclotron through the irradiation of oxygen-18.

Francium is a highly radioactive alkali metal with the symbol Fr and atomic number 87. It is one of the least stable elements on the periodic table, and it has no stable isotopes. The isotopes of francium are all radioactive, and the most commonly discussed isotopes are: 1. **Francium-223 (Fr-223)**: This is the most stable and the most naturally occurring isotope of francium, with a half-life of about 22 minutes.

Gadolinium (Gd) is a lanthanide element with atomic number 64 and has several isotopes. The most common isotopes of gadolinium include: 1. **Gadolinium-152 (Gd-152)**: This isotope has a natural abundance of about 0.14% and is stable. 2. **Gadolinium-154 (Gd-154)**: A stable isotope with a natural abundance of approximately 2.17%.

Gallium has two stable isotopes, which are: 1. **Gallium-69 (¹⁶⁹Ga)**: This isotope has 39 neutrons and is the more abundant of the two stable isotopes, comprising about 60.11% of natural gallium. 2. **Gallium-71 (¹⁷¹Ga)**: This isotope has 41 neutrons and makes up about 39.89% of naturally occurring gallium.

Germanium (Ge) has several isotopes, with the most stable and common ones being: 1. **Germanium-70 (¹⁷⁰Ge)**: This isotope has 32 neutrons and is stable. 2. **Germanium-72 (¹⁷²Ge)**: Also stable, this isotope has 34 neutrons. 3. **Germanium-73 (¹⁷³Ge)**: Another stable isotope with 35 neutrons.

Gold (Au) has a few naturally occurring isotopes, the most common of which is gold-197 (^197Au). This isotope is stable and makes up nearly all naturally occurring gold. Gold-197 has an atomic mass of approximately 196.96657 u. In addition to ^197Au, there are several radioactive isotopes of gold, though they are not found in nature and are typically produced in laboratories or through nuclear reactions.

Gold-198 (Au-198) is a radioactive isotope of gold. It has a mass number of 198, meaning it contains 118 neutrons and 79 protons in its nucleus. Au-198 is primarily produced through the neutron activation of gold-197, which is the most stable and abundant isotope of gold. **Key Characteristics of Gold-198:** 1.

Hafnium (Hf) is a chemical element with the atomic number 72 and has several isotopes. The isotopes of hafnium are distinguished by the number of neutrons in their nuclei, and they can be either stable or radioactive. Here are the key isotopes of hafnium: ### Stable Isotopes: 1. **Hafnium-174 (Hf-174)**: The most abundant stable isotope, making up about 32.5% of natural hafnium.

Hassium (Hs) is a synthetic element with the atomic number 108. It is a member of the transactinide series of elements and is classified in Group 8 of the periodic table. As of my last knowledge update in October 2023, hassium has a few known isotopes, with all of them being radioactive.

Holmium (Ho) has one stable isotope, holmium-165 (Ho-165), which makes up nearly all naturally occurring holmium. In addition to this stable isotope, holmium has several radioactive isotopes, with varying half-lives. The most notable radioactive isotopes of holmium include: 1. **Holmium-163 (Ho-163)** - This isotope is used in various applications, including neutron capture therapy and as a source of gamma radiation.

Hydrogen has three main isotopes, which vary based on the number of neutrons present in the nucleus: 1. **Protium (^1H)**: This is the most abundant isotope of hydrogen, consisting of one proton and no neutrons. It is represented as \(^1H\) or simply H. 2. **Deuterium (^2H or D)**: This isotope contains one proton and one neutron, giving it a mass number of two.

Indium has two stable isotopes: \(^{113}\text{In}\) and \(^{115}\text{In}\). 1. **\(^{113}\text{In}\)** - This isotope has a natural abundance of about 4.3%. It is a stable isotope, meaning it does not undergo radioactive decay. 2. **\(^{115}\text{In}\)** - This isotope is the most abundant, accounting for about 95.

Indium-111 (^{111}In) is a radioactive isotope of indium. It has a half-life of about 2.8 days and decays primarily via electron capture to stable tin-111 (^{111}Sn). Indium-111 is of significant interest in the field of nuclear medicine, particularly for its applications in diagnostic imaging and targeted therapy.

Iodine has several isotopes, the most notable of which are iodine-127, iodine-129, and iodine-131. 1. **Iodine-127 (¹²⁷I)**: This is the most stable and abundant isotope of iodine, making up about 100% of naturally occurring iodine. It has a half-life that is effectively infinite for practical purposes and is non-radioactive.

Iodine-123 (I-123) is a radioactive isotope of iodine that is commonly used in medical imaging and diagnostic procedures, particularly in the field of nuclear medicine. It has a half-life of approximately 13 hours, which makes it suitable for use in imaging studies because it decays quickly enough to reduce the patient's exposure to radiation while still allowing sufficient time for imaging procedures.

Iodine-129 (\(^{129}\text{I}\)) is a radioactive isotope of iodine. It has a half-life of approximately 15.7 million years, making it a long-lived isotope.

Iodine-131 (I-131) is a radioisotope of iodine, which is a chemical element with the symbol I and atomic number 53. I-131 has a half-life of about 8 days, which means that it takes approximately 8 days for half of a given quantity of the isotope to decay. This decay produces beta and gamma radiation.

An "iodine pit" is not a commonly used term in scientific literature or general discussions, so it may refer to a few different concepts depending on the context. However, the term could potentially be associated with various topics, such as: 1. **Iodine in Geology**: In geological contexts, "iodine pit" might refer to a location where iodine is extracted or found, often associated with certain types of mineral deposits.

Iofetamine (chemical name: **iodine-123 iofetamine**) is a radiopharmaceutical used primarily in the field of nuclear medicine for imaging of the brain. It is a specific tracer for assessing cerebral perfusion, which refers to the flow of blood to the brain tissue.

Iridium has several isotopes, with the two most stable and naturally occurring ones being: 1. **Iridium-191 (Ir-191)**: This isotope has a half-life of about 19.17 hours and decays to stable osmium-191. It is a product of the decay of heavier elements and is not found in significant amounts in nature.

Iridium-192 (Ir-192) is a radioactive isotope of the element iridium, which has the atomic number 77. It is part of the platinum group of metals and has various applications due to its radioactive properties. Iridium-192 is produced through the neutron activation of iridium-191, which is a stable isotope. ### Key Characteristics: - **Half-life:** Iridium-192 has a half-life of approximately 73.

Iron has several isotopes, which are variants of the element that have the same number of protons but different numbers of neutrons. The most stable and commonly occurring isotopes of iron are: 1. **Iron-54 (\(^{54}Fe\))**: This is the most abundant stable isotope, making up about 5.8% of natural iron.

Iron-55 (Fe-55) is a radioactive isotope of iron. It has a nuclear mass number of 55, meaning it has 26 protons and 29 neutrons in its nucleus. Iron-55 is produced as a decay product of manganese-55 and can also be formed in nuclear reactions. The half-life of Iron-55 is about 2.

Iron-56 (Fe-56) is a stable isotope of iron, which is one of the most abundant elements in the universe and a key component of many materials found on Earth. Isotopes of an element have the same number of protons but different numbers of neutrons. For Iron-56, it has 26 protons and 30 neutrons, giving it a total atomic mass of approximately 56 atomic mass units (amu).

Krypton (Kr) is a noble gas with atomic number 36. It has several isotopes, which are variants of the element that have the same number of protons but different numbers of neutrons. The most notable isotopes of krypton include: 1. **Krypton-78 (Kr-78)**: This isotope has 42 neutrons and is stable. 2. **Krypton-80 (Kr-80)**: This stable isotope has 44 neutrons.

Krypton-85 (Kr-85) is a radioactive isotope of the element krypton, which is a noble gas. It has a mass number of 85, meaning it has 36 protons and 49 neutrons in its nucleus. Krypton-85 is produced naturally in the atmosphere through the interaction of cosmic rays with stable krypton isotopes and is also released into the environment from certain human activities, primarily from nuclear reactors and radiological applications.

Lanthanum (La) has a few isotopes, but it has only one stable isotope: lanthanum-138 (¹³⁸La). This isotope accounts for nearly all naturally occurring lanthanum. In addition to the stable isotope, lanthanum has several radioactive isotopes. These isotopes include: 1. **Lanthanum-137 (¹³⁷La)**: A beta-emitting isotope with a half-life of about 6.

Lawrencium (Lr) is a synthetic element with the atomic number 103, and it is part of the actinide series. Due to its instability and short half-life, isotopes of lawrencium are not found naturally and have been produced in laboratories.

Lead has four stable isotopes and several unstable (radioactive) isotopes. The four stable isotopes of lead are: 1. **Lead-204 (\(^{204}\)Pb)**: This isotope has 82 protons and 122 neutrons. It is the least abundant stable isotope of lead. 2. **Lead-206 (\(^{206}\)Pb)**: This isotope has 82 protons and 124 neutrons.

Lithium has several isotopes, but the three most notable ones are: 1. **Lithium-6 (\(^6Li\))**: This isotope has three protons and three neutrons. It makes up about 7.5% of naturally occurring lithium. \(^6Li\) is known for its applications in nuclear fusion and as a coolant in nuclear reactors.

Livermorium (Lv) is a synthetic element with the atomic number 116. It belongs to the group of elements known as the post-transition metals. As of my last knowledge update in October 2021, livermorium has a limited number of known isotopes. The most stable and notable isotopes of livermorium are: 1. **Livermorium-293 (Lv-293)**: This isotope has been produced and has a half-life of approximately 60 milliseconds.

Lutetium (Lu) is a chemical element with the atomic number 71 and is part of the lanthanide series. It has several isotopes, but the most notable ones are as follows: 1. **Lutetium-175 (Lu-175)**: This is the most stable and abundant isotope of lutetium, making up about 97.4% of natural lutetium.

Magnesium has several isotopes, with the most notable being: 1. **Magnesium-24 (²⁴Mg)**: This is the most abundant isotope, making up about 79% of natural magnesium. It has 12 neutrons and is stable. 2. **Magnesium-25 (²⁵Mg)**: This isotope constitutes about 10% of natural magnesium. It has 13 neutrons and is also stable.

Manganese has several isotopes, with the most common being ^55Mn, which is stable. In total, there are 26 known isotopes of manganese, ranging from ^46Mn to ^75Mn. Here are some key points regarding manganese isotopes: 1. **Stable Isotope**: - **^55Mn**: The only stable isotope of manganese, making up nearly all natural manganese found in the environment.

Meitnerium (Mt) is a synthetic element with the atomic number 109 and is classified as a transactinide element in the periodic table. It is named in honor of physicist Lise Meitner. Due to its short half-life and the limited amount produced, there are only a few known isotopes of meitnerium.

Mendelevium (Md) is a synthetic element with the atomic number 101, and it is a member of the actinide series in the periodic table. As of my last update in October 2023, mendelevium has no stable isotopes. The known isotopes of mendelevium are all radioactive, and they have relatively short half-lives.

Mercury has several isotopes, which are varieties of mercury atoms that have the same number of protons but different numbers of neutrons. The most stable and commonly occurring isotopes of mercury are: 1. **Mercury-196 (²⁰⁶Hg)**: This is the most abundant isotope, making up about 30.6% of naturally occurring mercury.

Molybdenum (Mo) has several isotopes, which are variations of the element that contain different numbers of neutrons in their nuclei. The most stable and naturally occurring isotopes of molybdenum include: 1. **Molybdenum-92 (^92Mo)**: This isotope has 42 protons and 50 neutrons and is the most abundant isotope of molybdenum, making up about 14.8% of natural molybdenum.

Moscovium (Mc) is a synthetic element with the atomic number 115. As of my last knowledge update in October 2023, there are no stable isotopes of moscovium. The isotopes of moscovium that have been produced in laboratory settings are primarily radioactive and have very short half-lives.

Neodymium (Nd) has several isotopes, with the most stable and significant ones being: 1. **Neodymium-144 (Nd-144)**: This isotope has a half-life of about 2.29 million years and is stable. 2. **Neodymium-145 (Nd-145)**: Another stable isotope with no significant radioactivity. 3. **Neodymium-146 (Nd-146)**: This isotope has a half-life of about 5.

Neon has three stable isotopes: 1. **Neon-20 (¹⁴Ne)**: This is the most abundant isotope, making up about 90.48% of natural neon. It has 10 protons and 10 neutrons. 2. **Neon-21 (¹⁵Ne)**: This isotope is much less common, accounting for about 0.27% of natural neon. It has 10 protons and 11 neutrons.

Neptunium (Np) has several isotopes, with the most notable ones being: 1. **Neptunium-237 (Np-237)**: This is the most stable and prominent isotope of neptunium, with a half-life of about 2.14 million years. It is produced in nuclear reactors and is of interest due to its potential use in nuclear waste management and as a source of plutonium-238.

Neutronium is a hypothetical substance that consists almost entirely of neutrons. It is often discussed in the context of astrophysics and is theorized to be found in the cores of neutron stars, where extreme gravitational pressures force neutrons together in massive quantities. Since neutronium is made up entirely of neutrons, it doesn't have isotopes in the traditional sense as isotopes refer to variants of a chemical element that have the same number of protons but different numbers of neutrons.

A tetraneutron is a hypothetical nuclear structure consisting of four neutron particles bound together. Neutrons are subatomic particles that are found in the nucleus of atoms, and they have no electric charge. The concept of the tetraneutron arises in the field of nuclear physics and represents an attempt to understand how neutrons can interact with each other through the strong nuclear force.

Nickel has several isotopes, with the most notable ones being: 1. **Nickel-58 (¹⁵⁸Ni)**: This is the most abundant isotope of nickel, making up about 68% of natural nickel. It is stable. 2. **Nickel-60 (¹⁶⁰Ni)**: Another stable isotope, it accounts for about 26% of natural nickel.

Nickel-62 (\(^{62}\text{Ni}\)) is a stable isotope of nickel, which is a chemical element with the symbol Ni and atomic number 28. It has 28 protons and 34 neutrons in its nucleus. Nickel-62 is noteworthy for several reasons: 1. **Stability**: As a stable isotope, \(^{62}\text{Ni}\) does not undergo radioactive decay.

Nihonium (Nh) is a superheavy element with the atomic number 113. As of my last knowledge update in October 2023, nihonium has a few known isotopes, though due to its high instability and short half-lives, they are not found in nature and can only be produced artificially in laboratories.

Niobium (Nb) has several isotopes, but the two most significant ones are: 1. **Niobium-93 (³⁹Nb)**: This is the most stable and abundant isotope of niobium, comprising nearly 100% of naturally occurring niobium. It has a half-life that is effectively infinite in practical terms, and it does not undergo radioactive decay.

Nitrogen has several isotopes, which are atoms of the same element (nitrogen) that have the same number of protons but different numbers of neutrons. The most common isotopes of nitrogen are: 1. **Nitrogen-14 (\(^14N\))**: This is the most stable and abundant isotope, making up about 99.6% of natural nitrogen. It has 7 protons and 7 neutrons.

Nitrogen-13 (\(^{13}\text{N}\)) is a radioactive isotope of nitrogen. It has 7 protons and 6 neutrons in its nucleus, which gives it an atomic mass of approximately 13 atomic mass units (amu). This isotope is notable for its role in nuclear medicine, particularly in positron emission tomography (PET) imaging.

Nitrogen-15 tracing refers to a technique used in various fields, including biology, ecology, and environmental science, where the stable isotope nitrogen-15 (N-15) is tracked to study nitrogen cycling, plant nutrition, and ecosystem dynamics. Nitrogen-15 is a naturally occurring isotope of nitrogen, making up about 0.37% of all nitrogen in nature, while the more common isotope, nitrogen-14 (N-14), accounts for the majority.

Nobelium (No) is a synthetic element with the atomic number 102. It has no stable isotopes, and its isotopes are all radioactive. The most commonly referenced isotopes of nobelium are: 1. **Nobelium-254 (No-254)**: This is the most stable isotope of nobelium, with a half-life of about 55 minutes.

Oganesson (Og) is a synthetic element with the atomic number 118. It is a member of the noble gases group and is highly unstable, with a very short half-life. As of my last knowledge update in October 2023, only a few isotopes of oganesson have been identified, and they are primarily characterized by their mass numbers.

Osmium (Os) is a chemical element with the atomic number 76, and it has several isotopes, both stable and radioactive. The most notable isotopes of osmium are: 1. **Stable Isotopes:** - **Os-184**: Has a natural abundance of about 0.02%. - **Os-187**: The most abundant stable isotope, constituting about 1.97% of osmium found in nature.

Isotopes of oxygen are variants of the oxygen element that have the same number of protons (which is 8 for oxygen) but differ in the number of neutrons in their atomic nuclei. This difference in neutron number results in different atomic masses. The most common isotopes of oxygen are: 1. **Oxygen-16 (¹⁶O)**: This is the most abundant isotope, making up about 99.76% of natural oxygen.

Palladium (Pd) has a number of isotopes, but the most notable ones are: 1. **Palladium-102 (Pd-102)**: This is a stable isotope of palladium and makes up about 1.02% of natural palladium. 2. **Palladium-104 (Pd-104)**: This isotope is radioactive and has a half-life of about 3.1 hours. It decays primarily by beta decay.

Phosphorus has several isotopes, but the most important ones are: 1. **Phosphorus-31 (\(^31P\))**: This is the only stable isotope of phosphorus and constitutes 100% of naturally occurring phosphorus. It has 15 protons and 16 neutrons. 2. **Radioactive isotopes**: Phosphorus also has several radioactive isotopes, which are produced in laboratory settings or through nuclear reactions.

Phosphorus-32 (P-32 or ^32P) is a radioactive isotope of phosphorus. It has a total of 15 protons and 17 neutrons in its nucleus, giving it an atomic mass of approximately 32 atomic mass units (amu). P-32 is produced naturally in small quantities through the interaction of cosmic rays with stable phosphorus or can be produced artificially in a nuclear reactor. P-32 has a half-life of about 14.

Platinum has several isotopes, the most stable and naturally occurring ones being: 1. **Platinum-194 (^194Pt)**: This is the most abundant natural isotope of platinum, making up about 32% of natural platinum. 2. **Platinum-195 (^195Pt)**: This isotope accounts for approximately 34% of natural platinum. 3. **Platinum-196 (^196Pt)**: About 25% of natural platinum is in the form of this isotope.

Plutonium (Pu) has several isotopes, with the most notable being: 1. **Plutonium-238 (Pu-238)**: This isotope has a half-life of about 87.7 years and is used in radioisotope thermoelectric generators (RTGs) for powering spacecraft.

Plutonium-238 (Pu-238) is an isotope of plutonium, which is a heavy and radioactive metallic element. It has a half-life of about 87.7 years, making it relatively short-lived compared to some other isotopes of plutonium. Pu-238 is primarily used as a heat source in radioisotope thermoelectric generators (RTGs) — devices that convert the heat released by the decay of radioactive material into electrical energy.

Plutonium-239 (Pu-239) is a man-made isotope of plutonium, which is a radioactive element. It is notable for its use in nuclear reactors and nuclear weapons. Here are some key points about Pu-239: 1. **Isotope**: Plutonium has several isotopes, and Pu-239 is one of the most significant due to its properties.

Plutonium-240 (^240Pu) is a specific isotope of plutonium, which is a radioactive actinide metal. It is one of several isotopes of plutonium, with others including plutonium-239 (^239Pu), plutonium-241 (^241Pu), and plutonium-242 (^242Pu).

Plutonium-241 (Pu-241) is an isotope of plutonium, a heavy actinide metal. It is significant in the field of nuclear chemistry and nuclear engineering for several reasons: 1. **Nuclear Properties**: Plutonium-241 has a half-life of approximately 14.1 years. It is radioactive and undergoes beta decay, transforming into neptunium-241 (Np-241). This decay process emits beta particles and gamma radiation.

Plutonium-242 is an isotope of plutonium, which is a radioactive metallic element with the atomic number 94. It is one of the several isotopes of plutonium, and it has a relatively long half-life of about 376,000 years. This makes it one of the more stable isotopes of plutonium, though it is still radioactive.

Plutonium-244 (Pu-244) is an isotope of plutonium, a radioactive element with the atomic number 94. Plutonium itself is a heavy actinide metal that is primarily used as a fuel in nuclear reactors and in the manufacture of nuclear weapons.

Polonium is a radioactive element with the symbol Po and atomic number 84. It has several isotopes, of which the most notable include: 1. **Polonium-210 (Po-210)**: This is the most well-known isotope of polonium. It has a half-life of about 138 days and is a potent alpha-emitter. Po-210 has been used in various research applications and has gained notoriety due to its use in poisoning cases.

Polonium-210 is a radioactive isotope of polonium, a chemical element with the symbol Po and atomic number 84. It was discovered in 1940 by the scientists Marie Curie and her husband Pierre Curie, who named it after Poland. Polonium-210 is one of the most well-known isotopes of polonium, primarily due to its intense radioactivity and its use in various applications.

Potassium has several isotopes, but the most notable ones are: 1. **Potassium-39 (⁴⁰K)**: This is the most abundant isotope, making up about 93.26% of natural potassium. It is stable and does not undergo radioactive decay. 2. **Potassium-40 (⁴⁰K)**: This isotope is radioactive and makes up about 0.012% of natural potassium. It has a half-life of approximately 1.

Potassium-40 (K-40 or ^40K) is a naturally occurring isotope of potassium, which is a vital nutrient for various biological and geological processes. It is one of the three stable isotopes of potassium, alongside Potassium-39 (^39K) and Potassium-41 (^41K). K-40 is notable because it is radioactive and has a long half-life of about 1.248 billion years, which means it decays very slowly.

Praseodymium, which has the atomic number 59, has several isotopes, with a total of 6 known isotopes ranging from \(\text{Pr}^{125}\) to \(\text{Pr}^{135}\). The most stable and naturally occurring isotopes of praseodymium are: 1. **Praseodymium-141 (\(^{141}\text{Pr}\))**: This is the most abundant isotope, constituting about 99.

Promethium (Pm) is a rare and radioactive element with the atomic number 61. It has a number of isotopes, most of which are unstable and radioactive. The most notable isotopes of promethium include: 1. **Promethium-145 (Pm-145)**: This isotope has a half-life of about 17.7 hours and decays into Neodymium-145.

Protactinium (Pa) has several isotopes, but the most notable ones are: 1. **Protactinium-231 (Pa-231)**: This is the most stable and widely recognized isotope of protactinium. It has a half-life of about 32,760 years and is produced from the decay of uranium-235. It is used in various scientific research applications, including studies related to nuclear chemistry and geology.

Radium has several isotopes, the most notable of which are Radium-226 and Radium-228. Here's a brief overview of these isotopes: 1. **Radium-226**: - It is the most stable and common isotope of radium. - It has a half-life of about 1,600 years and decays primarily through alpha decay into radon-222.

Radon is a radioactive noble gas with the symbol Rn and atomic number 86. It has several isotopes, with the most notable being: 1. **Radon-222 (²²²Rn)**: The most stable and abundant isotope, with a half-life of about 3.8 days. It is produced naturally from the decay of uranium-238 and is significant in environmental studies due to its presence in soil and groundwater.

Radon-222 (Rn-222) is a radioactive isotope of radon, a noble gas that occurs naturally in the environment as a decay product of uranium and thorium. It is colorless, odorless, and tasteless, making it undetectable without specialized equipment. Radon-222 has a half-life of about 3.8 days, meaning that it decays relatively quickly compared to some other radioactive isotopes.

Rhenium (Re) is a transition metal with atomic number 75. It has several isotopes, but the most notable ones are: 1. **^185Re**: This is the most stable and abundant isotope of rhenium, with a half-life of approximately 4.0 × 10^10 years. It is a non-radioactive isotope and is commonly used in various applications, including catalysts and electronics.

Rhodium (Rh) has several isotopes, but the most notable ones are: 1. **Rhodium-103 (Rh-103)**: This is the only stable isotope of rhodium and makes up nearly all naturally occurring rhodium. It has a nuclear spin of 1/2 and is commonly used in various applications, including catalytic converters and jewelry.

Roentgenium (Rg) is a synthetic element with the atomic number 111. It is highly unstable and radioactive, and as of my last update, only a few isotopes of roentgenium have been produced. The known isotopes of roentgenium include: 1. **Roentgenium-282 (Rg-282)**: This isotope has a half-life of approximately 2.1 milliseconds.

Rubidium (Rb) has several known isotopes, with the most notable ones being rubidium-85 (¹⁸⁵Rb) and rubidium-87 (¹⁸⁷Rb). Here are some details about these isotopes: 1. **Rubidium-85 (¹⁸⁵Rb)**: - **Natural Abundance**: Approximately 72.2% of natural rubidium is ¹⁸⁵Rb.

Rubidium-82 (Rb-82) is a radioactive isotope of rubidium, which is a soft, silvery-white metallic element. Rb-82 is notable for its application in medical imaging, particularly in positron emission tomography (PET) scans. In medical contexts, Rb-82 is used as a positron-emitting radiotracer for myocardial perfusion imaging.

Ruthenium has several isotopes, with a total of 7 naturally occurring and synthetic isotopes known. Here are some of the notable isotopes of ruthenium: 1. **Ruthenium-96 (Ru-96)**: This is the most stable and abundant isotope, with a half-life of about 373.59 days. It primarily decays by beta decay.

Rutherfordium (Rf) is a synthetic element with the atomic number 104. It has no stable isotopes, and all of its isotopes are radioactive. The most notable isotopes of rutherfordium include: 1. **Rutherfordium-261**: This is the most stable isotope, with a half-life of about 2.5 minutes. 2. **Rutherfordium-260**: This isotope has a half-life of approximately 2.2 minutes.

Samarium (Sm) is a chemical element with the atomic number 62. It has several isotopes, with the most stable and common ones being: 1. **Samarium-144 (^144Sm)**: This isotope has a half-life of about journalists days and is one of the most stable isotopes of samarium.

Samarium-147 (Sm-147) is a radioactive isotope of the element samarium, which has the atomic number 62. It is one of the isotopes of samarium, with a notable half-life of about 106 billion years, making it one of the more stable isotopes of this element. Samarium-147 decays through beta decay to neodymium-147 (Nd-147).

Scandium has several isotopes, the most notable of which are: 1. **Scandium-45 (⁴⁵Sc)**: This is the only stable isotope of scandium and makes up nearly 100% of naturally occurring scandium. It has a nuclear spin of 7/2 and is not radioactive.

Scandium-44 (\(^{44}\text{Sc}\)) is a radioactive isotope of the element scandium. It has a mass number of 44 and is notable for its use in medical applications, particularly in positron emission tomography (PET) imaging. Scandium-44 decays via beta-plus decay, emitting positrons and gamma radiation.

Seaborgium (Sg) is a synthetic element with atomic number 106. It is part of the transactinide series and was first synthesized in 1974. Due to its very short half-life, seaborgium has no stable isotopes. The known isotopes of seaborgium are all radioactive.

Selenium has several isotopes, which are variations of the element that have the same number of protons but different numbers of neutrons. The most stable and common isotopes of selenium are: 1. **Selenium-74 (Se-74)**: This isotope has 34 protons and 40 neutrons and is one of the most abundant isotopes of selenium.

Selenium 79 refers to a specific version of the Selenium browser automation framework. Selenium is widely used for automating web applications for testing purposes but is also used for web scraping and other browser automation tasks. Each version of Selenium typically includes various updates, bug fixes, and new features. For instance, Selenium 79 might have introduced enhancements to WebDriver, added support for new browser versions, improved existing functionalities, or fixed issues observed in earlier versions.

Silicon has several isotopes, which are variations of the silicon atom that have the same number of protons (14) but different numbers of neutrons. The stable isotopes of silicon are: 1. **Silicon-28 (Si-28)**: This is the most abundant isotope, making up about 97.2% of natural silicon. It has 14 protons and 14 neutrons.

Silver has several isotopes, but the two most notable ones are: 1. **Silver-107 (\(^{107}\)Ag)**: This is the most stable and abundant isotope of silver, comprising about 51.8% of natural silver. Silver-107 has a nuclear spin of 1/2 and is used in various applications, including in certain types of nuclear magnetic resonance (NMR) spectroscopy.

Sodium (Na) has several isotopes, but the most notable ones are: 1. **Sodium-23 (Na-23)**: This is the only stable isotope of sodium and accounts for almost all naturally occurring sodium. It has 11 protons and 12 neutrons. 2. **Sodium-22 (Na-22)**: This is a radioactive isotope of sodium with a half-life of about 2.6 years.

Strontium has several isotopes, but the most notable ones are: 1. **Strontium-84 (Sr-84)**: This is the most abundant stable isotope of strontium, making up about 0.56% of naturally occurring strontium. 2. **Strontium-86 (Sr-86)**: This is another stable isotope, comprising about 9.86% of natural strontium.

Strontium-89 is a radioactive isotope of strontium, denoted as ^89Sr. It is produced as a byproduct of nuclear reactions and is characterized by its half-life of approximately 50.5 days. Strontium-89 decays by beta decay, emitting beta particles and gamma rays, which can be detected and measured.

Strontium-90 (^90Sr) is a radioactive isotope of strontium, which is a chemical element with the symbol Sr and atomic number 38. It is produced primarily as a byproduct of nuclear fission in reactors and during atomic bomb explosions. Strontium-90 has a half-life of approximately 28.8 years, which means it takes this amount of time for half of a given amount of the isotope to decay.

Sulfur has several isotopes, which are variants of the sulfur atom that have the same number of protons but different numbers of neutrons. The most common isotopes of sulfur are: 1. **Sulfur-32 (²³²S)**: This is the most abundant isotope, accounting for about 95% of naturally occurring sulfur. It has 16 protons and 16 neutrons.

Carbonate-associated sulfate (CAS) refers to sulfate ions that are incorporated into carbonate minerals, particularly in sedimentary rocks. This form of sulfate is typically found in carbonates like calcite or aragonite, which are common in marine and freshwater environments.

Sulfur isotope biogeochemistry is the study of sulfur in various biological, geological, and chemical processes, focusing on the variations in sulfur isotopes and how they reflect environmental conditions, biological activity, and geochemical cycles.

Tantalum has two stable isotopes: **Tantalum-181 (Ta-181)** and **Tantalum-180 (Ta-180)**. The most abundant isotope is Ta-181, which constitutes almost all naturally occurring tantalum.

Technetium (Tc) is a chemical element with atomic number 43 and is notable for being the first artificially produced element. It has several isotopes, with the most significant ones being: 1. **Technetium-97 (Tc-97)**: This isotope has a half-life of about 4.2 million years and is one of the more stable isotopes. It is produced in trace amounts in nuclear reactors and is used in some medical applications.

Technetium-99 (Tc-99) is a radioactive isotope of technetium, which is a chemical element with the symbol Tc and atomic number 43. Tc-99 is significant in various fields, particularly in nuclear medicine. ### Properties: - **Half-Life**: Tc-99 has a relatively short half-life of about 6 hours. This means that it decays relatively quickly, which is advantageous for medical applications as it limits the patient's exposure to radiation.

Tellurium (Te) has several isotopes, both stable and radioactive. The most common isotopes of tellurium are: 1. **Stable Isotopes:** - **Te-120**: The most abundant stable isotope, constituting about 33% of natural tellurium. - **Te-122**: Another stable isotope, making up about 52% of natural tellurium.

Tennessine (Ts) is a synthetic element with the atomic number 117. As of now, there are no stable isotopes of tennessine, and all of its isotopes are radioactive. The isotopes of tennessine that have been identified include: 1. **Tennessine-294 (Ts-294)**: This is the most stable isotope of tennessine, with a half-life of approximately 78 milliseconds.

Terbium (Tb) is a chemical element with the atomic number 65. It has several isotopes, but only a few are stable. The most important isotopes of terbium include: 1. **Terbium-159 (Tb-159)**: This is the only stable isotope of terbium. It comprises about 100% of naturally occurring terbium.

Thallium (Tl) has several isotopes, which are variants of the element with the same number of protons but different numbers of neutrons. Naturally occurring thallium has two stable isotopes: 1. **Thallium-203 (Tl-203)**: - Number of protons: 81 - Number of neutrons: 122 - Natural abundance: About 29.5%.

Thorium is a radioactive element with several isotopes, the most notable of which are: 1. **Thorium-232 (Th-232)**: This is the most abundant and stable isotope of thorium, making up about 99.98% of naturally occurring thorium. It has a half-life of approximately 14.05 billion years and is used in nuclear reactors and as a source material for nuclear fuel.

Thorium-232 is a naturally occurring isotope of thorium, which is a heavy, radioactive element with the atomic number 90. It is one of the most stable isotopes of thorium and has a half-life of about 14.05 billion years, making it significantly long-lived compared to other radioactive isotopes.

Thulium (Tm) is a chemical element with the atomic number 69. It has several isotopes, of which the most notable are: 1. **Tl-169**: This is the most stable and abundant isotope of thulium, making up nearly all naturally occurring thulium. It has a half-life of 1,457 years and is stable. 2. **Tl-168**: This isotope is radioactive and has a half-life of about 93 minutes.

Tin has several isotopes, with the most common being tin-120, tin-116, tin-117, tin-118, tin-119, and tin-121.

Titanium has several isotopes, but the most notable ones are: 1. **Titanium-46 (Ti-46)**: This isotope has 22 neutrons and is one of the stable isotopes of titanium. 2. **Titanium-47 (Ti-47)**: Another stable isotope, it has 23 neutrons. 3. **Titanium-48 (Ti-48)**: The most abundant stable isotope, comprising about 73.8% of naturally occurring titanium.

Tungsten (W) has several isotopes, with the most stable and naturally occurring ones being: 1. **W-180**: This is the most abundant isotope, making up about 0.12% of natural tungsten. 2. **W-182**: The second most abundant isotope, constituting about 26.3% of natural tungsten. 3. **W-183**: This isotope makes up around 14.3% of natural tungsten.

Unbinilium, with the temporary symbol Ubn and atomic number 120, is a synthetic element that has not yet been observed in significant quantities. As of my last knowledge update in October 2023, no isotopes of unbinilium have been definitively produced and studied, primarily due to the challenges associated with synthesizing superheavy elements.

Ununennium is the temporary systematic element name for element 119 in the periodic table, which is currently not yet discovered or observed. It is a synthetic element predicted to belong to the group of alkali metals. Since ununennium has not been synthesized, there are no known isotopes or empirical data about its isotopes. However, theoretical predictions suggest that ununennium would possess several isotopes, like many other elements, based on its potential nuclear configurations.

Uranium has several isotopes, but the most significant ones are: 1. **Uranium-238 (U-238)**: This is the most abundant isotope of uranium, comprising about 99.3% of natural uranium. U-238 is not fissile (cannot sustain a nuclear chain reaction) but can be converted into plutonium-239 in a reactor environment. 2. **Uranium-235 (U-235)**: This isotope constitutes about 0.

Uranium-232 (^232U) is a radioactive isotope of uranium. It is a minor isotope that occurs naturally in trace amounts in uranium ores, alongside more prominent isotopes like uranium-238 (^238U) and uranium-235 (^235U). Here are some key points about uranium-232: 1. **Radioactive Properties**: ^232U has a half-life of about 68.8 years, which means that it decays relatively slowly compared to some other isotopes.

Uranium-233 (U-233) is a radioactive isotope of uranium. It is one of the isotopes of uranium that can be used in nuclear reactions, particularly in reactors and for the production of nuclear energy. Here are some key points about U-233: 1. **Production**: U-233 is primarily produced through the neutron irradiation of thorium-232 (Th-232), which captures a neutron to become Th-233.

Uranium-234 (U-234) is an isotope of uranium, which is a heavy metal known for its use in nuclear fuel and weapons. U-234 is a radionuclide, meaning it is radioactive and undergoes decay over time. It has a relatively long half-life of about 245,500 years, which allows it to exist in significant quantities in nature, albeit at low concentrations.

Uranium-235 (U-235) is one of the isotopes of uranium, a heavy metal that is used as a fuel in nuclear reactors and in the production of nuclear weapons. U-235 is particularly significant because it is fissile, meaning it can sustain a nuclear fission reaction when it absorbs a neutron.

Uranium-236 (U-236) is a radioactive isotope of uranium. It is one of the isotopes that can be produced through the capture of neutrons by uranium-235 (U-235), which is a more abundant isotope commonly used in nuclear reactors and weapons. U-236 has a relatively low occurrence in nature and is generally the result of nuclear reactions, such as those that occur in nuclear reactors or during the detonation of nuclear weapons.

Uranium-238 (U-238) is one of the isotopes of uranium, which is a naturally occurring element found in the Earth's crust. It is the most abundant isotope of uranium, constituting about 99.3% of natural uranium. U-238 is a heavier isotope, with 146 neutrons and 92 protons in its nucleus, giving it an atomic mass of approximately 238 atomic mass units (amu).

Vanadium, which has the atomic number 23, has several isotopes, with the most stable and well-known ones being: 1. **Vanadium-50 (⁵⁰V)**: This is the most abundant stable isotope, making up about 0.25% of natural vanadium. It has a mass number of 50 and is not radioactive.

Xenon (Xe) is a noble gas that has several isotopes, which are variations of the element with the same number of protons but different numbers of neutrons. The most common isotopes of xenon, along with their relative abundances and characteristics, include: 1. **Xenon-124 (Xe-124)**: This isotope has 54 protons and 70 neutrons. It is stable and constitutes about 0.1% of natural xenon.

Xenon-135 (^135Xe) is a radioactive isotope of xenon, which is a noble gas. It is notable for its role in nuclear reactors and its properties in nuclear physics. Here are some key points about Xenon-135: 1. **Nuclear Properties**: It has a half-life of about 9.2 hours, decaying primarily through beta decay to iodine-135 (^135I).

Ytterbium (Yb) is a chemical element with the atomic number 70 and belongs to the lanthanide series. It has several isotopes, which are variants of the element with the same number of protons but different numbers of neutrons.

Yttrium has several isotopes, with the most notable being: 1. **Yttrium-89 (Y-89)**: The most stable and abundant isotope, making up nearly 100% of natural yttrium. It has a half-life of about 64 hours when produced artificially. It is used in various applications, including medicine and as a tracer in certain types of studies.

Yttrium-90 (\(^{90}\text{Y}\)) is a radioactive isotope of yttrium. It has a mass number of 90 and is commonly known for its applications in the field of medicine, particularly in radiation therapy for cancer treatment. Yttrium-90 is a beta emitter, meaning it decays by emitting beta particles.

Zinc has several isotopes, but the most notable ones are: 1. **Zinc-64 (Zn-64)**: This is the most abundant isotope of zinc, making up about 48.6% of natural zinc. It has 30 protons and 34 neutrons. 2. **Zinc-66 (Zn-66)**: This isotope constitutes about 27.9% of natural zinc and has 30 protons and 36 neutrons.

Zirconium (Zr) is a chemical element with the atomic number 40 and has several isotopes. The isotopes of zirconium range from Zr-90 to Zr-110, with Zr-90 being the most abundant and stable isotope. Here’s a brief overview of its isotopes: 1. **Zr-90**: This is the most common and stable isotope, making up about 51.4% of natural zirconium.

Lists of isotopes by element typically refer to tables or databases that categorize and provide information on the different isotopes of each chemical element. An isotope is a variant of a chemical element that has the same number of protons (and thus the same atomic number) but a different number of neutrons, resulting in a different atomic mass.

Medical isotopes are radioactive isotopes used in the diagnosis and treatment of various medical conditions, primarily in the field of nuclear medicine. These isotopes are utilized for their ability to emit radiation, which can be detected by imaging equipment for diagnostic purposes or used for targeted therapy.

Metastable isotopes, also known as isomers, are nuclei that exist in an excited state for a relatively long period of time compared to typical nuclear decay processes. While most isotopes will decay quickly to a more stable state, metastable isotopes have higher energy levels that do not decay immediately and can exist for extended periods, ranging from microseconds to years.

The Tables of Nuclides, also known as nuclide charts or nuclide diagrams, are comprehensive graphical representations that display information about the various isotopes (nuclides) of chemical elements. Each nuclide is characterized by its number of protons (atomic number), number of neutrons, and its nuclear properties, such as stability, half-life, decay modes, and abundance.

The Karlsruhe Nuclide Chart is a visual representation of all known nuclides (different isotopes of elements) arranged according to their atomic number (number of protons) and neutron number. It serves as a comprehensive tool for displaying information about isotopes, including their stability, decay modes, and other nuclear properties.

The "List of Nuclides" refers to a comprehensive catalog of all known isotopes (nuclides) of the chemical elements, including both stable and radioactive forms. Each nuclide is characterized by its atomic number (the number of protons), mass number (the total number of protons and neutrons), and sometimes its specific energy states and half-lives if it is radioactive.

A Table of Nuclides is a comprehensive chart that displays isotopes of all known chemical elements, organized primarily by their atomic number (number of protons) along one axis and their mass number (total number of protons and neutrons) along the other axis. It provides valuable information about the stability, decay modes, and properties of various isotopes.

A segmented, narrow table of nuclides is a graphical representation that organizes nuclides (different isotopes of elements) according to their atomic number (protons) and mass number (protons plus neutrons). The table is often segmented to reflect various properties of the nuclides, such as stability, mode of decay, or type of nuclear interactions.

CERN-MEDICIS (MEDical Information and Communication for Innovative Solutions) is a project developed by CERN, the European Organization for Nuclear Research, aimed at advancing medical applications of particle physics technologies. One of its main objectives is to support research in the field of medical isotopes, particularly for cancer treatment and imaging. MEDICIS focuses on the production of innovative radioisotopes that can be used in targeted therapies and diagnostics.

Clumped isotopes refer to isotopes of elements that are found together in a molecule more frequently than would be expected from random distribution. In the context of geochemistry and paleoclimatology, clumped isotope analysis typically involves measuring the abundance of heavy isotopes (like ^13C, ^15N, or ^18O) in carbonates, water, or organic materials.

Doubly labeled water (DLW) is a method used primarily in ecological and metabolic studies to measure energy expenditure and metabolic rates in free-ranging animals, including humans. The technique involves the use of two stable isotopes of water: deuterium (^2H or D) and oxygen-18 (^18O). **How it works:** 1.

Early Cambrian geochemical fluctuations refer to the significant changes in the chemical composition of Earth's oceans and atmosphere that occurred during the Early Cambrian period, which spanned from about 541 to 485 million years ago. This period is noted for the "Cambrian Explosion," a time of rapid diversification of life forms, particularly the evolution of many major groups of animals.

The Global Meteoric Water Line (GMWL) is a key concept in hydrology and isotope geology. It represents the relationship between the stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O) in natural water samples, particularly meteoric water (i.e., water that precipitates from the atmosphere, such as rain and snow).

Isotope analysis is a scientific technique used to determine the relative abundance of different isotopes of the same element within a sample. Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Isotope analysis in archaeology is a scientific technique used to study the chemical signatures of materials, particularly human remains, animal bones, and artifacts, through the measurement of isotopic ratios. Isotopes are variants of elements that have the same number of protons but different numbers of neutrons, leading to differences in their atomic mass. The ratios of these isotopes can provide valuable information about past environments, diets, migration patterns, and social structures.

The isotopic resonance hypothesis is a concept in the field of chemistry and physics that relates to the behavior of isotopes of elements and the effects they have on chemical reactions, particularly in biochemical processes. While specific details may vary and definitions can differ among disciplines, the hypothesis generally suggests that isotopes can exhibit different resonance behaviors due to their nuclear properties, which can influence molecular interactions and reaction pathways.

An isotopologue is a type of molecule that differs from another molecule by having different isotopes of one or more of its constituent atoms. Isotopes are variants of the same chemical element that have the same number of protons but different numbers of neutrons, which results in different atomic masses. For example, consider the molecule water (H₂O). The common isotopologue of water consists of two protium isotopes (¹H) and one oxygen isotope (¹⁶O).

A list of radioactive nuclides by half-life typically categorizes isotopes based on their decay rates. Each isotope's half-life is the time it takes for half of a sample of that isotope to decay.

Mass-independent fractionation (MIF) is a process that causes isotopes of an element to be distributed in a way that is not solely dependent on their mass. This phenomenon often occurs in specific chemical reactions or under certain environmental conditions, particularly in relation to non-standard isotopic processes. MIF is particularly well-documented in the context of certain elements, such as sulfur, oxygen, and mercury.

A monoisotopic element is an element that has only one stable isotope, meaning that all the atoms of that element have the same atomic mass and nuclear composition. Such elements do not have multiple isotopes that are stable and can be found in nature. For example, the element fluorine (atomic number 9) has only one stable isotope, fluorine-19. Therefore, fluorine is considered a monoisotopic element.

A mononuclidic element is an element that has only one stable isotope. In other words, all the atoms of a mononuclidic element are identical in terms of their nuclear composition, and they do not have any other stable isotopes. This means that every atom of the element has the same number of protons and neutrons in its nucleus.

NAIL-MS (National Institute of Health - Multiple Sclerosis) is a research initiative focused on understanding multiple sclerosis (MS) and advancing treatment options. NAIL-MS aims to establish a national network of clinical research sites, collect comprehensive data on MS patients, and promote collaboration among researchers and clinicians. The project emphasizes the importance of patient involvement in research, aiming to collect diverse data that can facilitate better understanding of the disease’s mechanisms, progression, and treatment outcomes.

Natural abundance refers to the relative proportions of different isotopes of a particular chemical element found in nature. Each element can consist of various isotopes, which are atoms with the same number of protons but different numbers of neutrons. This leads to variations in their atomic mass. The natural abundance of an isotope is typically expressed as a percentage of the total amount of that element present in a given sample.

Natural isotopes are variants of a chemical element that have the same number of protons in their atomic nuclei (which defines the element) but differ in the number of neutrons. This difference in neutron numbers results in different mass numbers for the isotopes. For example, carbon has two stable isotopes: 1. **Carbon-12 (\(^{12}C\))**, which has 6 protons and 6 neutrons.

Position-specific isotope analysis (PSIA) is a sophisticated analytical technique used primarily in the fields of chemistry, biochemistry, and environmental science. This method focuses on measuring the isotopic composition of specific positions within a molecule, allowing researchers to gain insights into the molecular structure, metabolic pathways, and overall origin of the compound being studied.

Reference materials for stable isotope analysis are substances with well-characterized isotopic compositions that are used to calibrate and validate analytical instruments and methods involved in the measurement of stable isotopes. These materials help ensure that the results obtained from isotope analyses are accurate, reproducible, and comparable across different laboratories. ### Key Features of Reference Materials: 1. **Characterization**: Reference materials have precisely determined isotopic ratios, which are established through consensus methods or extensive inter-laboratory comparison.

The stable isotope composition of amino acids refers to the ratio of stable isotopes present in the amino acid molecules. Stable isotopes are non-radioactive variants of elements that have the same number of protons but differ in the number of neutrons. For example, carbon (C) has two stable isotopes: carbon-12 (^12C) and carbon-13 (^13C).

Stable isotope ratio refers to the relative abundance of different stable isotopes of an element in a given sample. Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. Stable isotopes do not undergo radioactive decay, making them useful for various scientific applications. For example, carbon has two stable isotopes: carbon-12 (^12C) and carbon-13 (^13C).

A stable nuclide is an isotope of an element that does not undergo radioactive decay over time. In other words, stable nuclides have a balance of protons and neutrons in their nuclei that allows them to remain intact indefinitely, without transforming into other elements or isotopes. Stability in nuclides is determined by the ratio of neutrons to protons and the forces at play within the atomic nucleus.