An atom (nuclear) with the same nuclear charge but different atomic mass is called an isotope. Since the discovery of radioactivity at the end of the 19th century, more than 30 radioactive elements have been discovered by the early 20th century, and it has been shown that some radioactive elements, although significantly different in radioactivity, are chemically identical. In 1910, the British chemist F. Soddy proposed a hypothesis that chemical elements have different physicochemical properties with different atomic weight and radioactivity. These variants should be in the same position of the periodic table, called isotopes. Soon, the atomic weight of a lead obtained from different radioactive elements was 206.08, and the other was 208. In 1897, British physicist W. Thomson discovered electrons. In 1912, he improved the instrument for measuring electrons and used magnetic fields. A magnetic separator (predecessor of the mass spectrometer) was fabricated. When he measured with helium, no matter how it was purified, two parabolas were obtained on the screen, one representing the mass of 20 and the other representing the mass of 22. This is the first stable isotope discovered, that is, a radioactive isotope. When FW Aston made the first mass spectrometer, it was further proved that helium did have two isotopes with different atomic masses and more than 200 isotopes were found from more than 70 other elements. So far, 109 elements have been discovered, and only 20 elements have not found stable isotopes, but all elements have radioisotopes. Most of the natural elements are a mixture of several isotopes, with more than 300 stable isotopes and more than 1,500 radioisotopes.
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Amino compound
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Oxy-containing amino compound
Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts thereof
Acyclic monoamines, polyamines and their derivatives and salts
Amide compound
Sulfonic acid amino compound
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Alcohols, phenols, phenolic compounds and derivatives
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2-cycloalcohol
Halogenated, sulfonated, nitrated or nitrosated derivatives of alcohols
Extremely halogenated, sulfonated, nitrated or nitrosated derivatives of phenols
Phenol and its halogenated, sulfonated, nitrated or nitrosated derivatives
Acyclic alcohol
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Nitrogen-containing compound
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Nitrile compound
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Organic derivative of hydrazine or hydrazine
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Terpenoid
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Ether compounds and their derivatives
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Ether, ether alcohol
Halogenation, sulfonation, nitration or nitrosation of ethers, ether alcohols, ether phenols
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Aldehyde
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Carboxylic compounds and derivatives
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Cyclic carboxylic acid
Halogenation, sulfonation, nitration or nitrosation of carboxylic acids
Halogenation, sulfonation, nitration or nitration of carboxylic anhydrides
Carboxylic acid halide
Carboxylic esters and their derivatives
Salt of carboxylic acid ester and its derivatives
Acyclic carboxylic acid
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Hydrocarbon compounds and their derivatives
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Aromatic hydrocarbon
Cyclic hydrocarbon
Hydrocarbon sulfonate
Hydrocarbon halide
Hydrocarbon nitrite
Acyclic hydrocarbon
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Ketone compound
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Alkyl ureas and their derivatives and salts
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Inorganic acid ester
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Heterocyclic compound
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Diazo, azo or azo compound
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Organosilicon compound
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Organometallic compound
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Organic palladium
Organic germanium, cobalt, strontium, barium, gallium, germanium, germanium, germanium, germanium, etc.
Organic calcium
Zirconium
Organic potassium
Organic
Organic lithium
Organic
Organic aluminum
Organotin
Organic manganese
Organic sodium
Organic nickel
Organic titanium
Organic iron
Organic copper
Organotin
Organic zinc
Organic
Organic
Organic germanium, mercury, silver, platinum, etc.
Organic germanium, antimony, bismuth, tungsten, antimony, bismuth, lead, vanadium, molybdenum, chromium, antimony, etc.
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Organic sulfur compound
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Organic phosphine compound
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Organometallic salt
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Organic fluorine compound
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Fluorobenzoic acid series
Fluorobenzonitrile series
Fluorobenzaldehyde series
Fluorobenzyl alcohol series
Fluoroanisole series
Fluoroaniline series
Fluorophenylacetic acid series
Fluorophenol series
Fluorobenzoic acid series
Fluoronitrobenzene series
Fluoropyridine series
Potassium fluoroborate series
Fluorobenzyl alcohol series
Fluorotoluene series
Fluorine red series
Fluoroethane series
Fluoropropane series