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atomic masses | A Wisdom Archive on atomic masses | | atomic masses A selection of articles related to atomic masses | |
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atomic masses
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| ARTICLES RELATED TO atomic masses | | | |  atomic masses: Encyclopedia II - Noble gas - ChemistryBecause of their unreactivity, the noble gases were not discovered until 1868, when helium was detected spectrographically in the Sun. The isolation of helium on Earth had to wait until 1895. The noble gases have very weak inter-atomic forces of attraction, and consequently very low melting points and boiling points. This is why they are all gases under normal conditions, even those with larger atomic masses than many normally solid elements.
The periodic table contains an empty space under radon, with atomic number 118. This indicates the existence, albeit short-lived, of an as yet undiscovered noble gas, which ...
See also:Noble gas, Noble gas - Etymology, Noble gas - Chemistry, Noble gas - Applications, Noble gas - Physical Properties Read more here: » Noble gas: Encyclopedia II - Noble gas - Chemistry |
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| | | | | | atomic masses: Encyclopedia II - Technetium - Applications
Technetium - Nuclear medicine.
Tc-99m ("m" indicates that this is a metastable nuclear isomer) is used in radioactive isotope medical tests, for example as a radioactive tracer that medical equipment can detect in the body. It is well suited to the role because it emits readily detectable 140 keV gamma rays, and it has a short half-life of 6.01 hours (meaning it has almost completely decayed to Tc-99 in 24 hours). In the book Technetium by Klaus Schwochau, 31 different radiopharmaceuticals based on Tc-99m ...
See also:Technetium, Technetium - Notable characteristics, Technetium - Applications, Technetium - Nuclear medicine, Technetium - Industrial, Technetium - History, Technetium - Pre-discovery search, Technetium - Disputed 1925 discovery, Technetium - Official discovery and later history, Technetium - Occurrence and production, Technetium - Part of radioactive waste, Technetium - Reductive immobilization, Technetium - Chemical means, Technetium - Biological means, Technetium - Isotopes, Technetium - Stability of technetium isotopes, Technetium - Precautions Read more here: » Technetium: Encyclopedia II - Technetium - Applications |
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| | | | | | | atomic masses: Encyclopedia II - Technetium - Notable characteristics Technetium is a silvery-grey radioactive metal with an appearance similar to platinum. However, it is commonly obtained as a grey powder. Its position in the periodic table is between rhenium and manganese and as predicted by the periodic law its properties are intermediate between those two elements. This element is unusual among the lighter elements because it has no stable isotopes and is therefore extremely rare on Earth.
The metal form of technetium slowly tarnishes in moist air. Its oxides are TcO2 and Tc2O ...
See also:Technetium, Technetium - Notable characteristics, Technetium - Applications, Technetium - Nuclear medicine, Technetium - Industrial, Technetium - History, Technetium - Pre-discovery search, Technetium - Disputed 1925 discovery, Technetium - Official discovery and later history, Technetium - Occurrence and production, Technetium - Part of radioactive waste, Technetium - Reductive immobilization, Technetium - Chemical means, Technetium - Biological means, Technetium - Isotopes, Technetium - Stability of technetium isotopes, Technetium - Precautions Read more here: » Technetium: Encyclopedia II - Technetium - Notable characteristics |
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| | | | | atomic masses: Encyclopedia II - Technetium - History
Technetium - Pre-discovery search.
For a number of years there was a gap in the periodic table between molybdenum (element 42) and ruthenium (element 44). Many early researchers were eager to be the first to discover and name the missing element; its location in the table suggested that it should be easier to find than other undiscovered elements. It was first thought to have been found in platinum ores in 1828. It was given the name polinium but it turned out to be impure iridium. Then in 1846 the element ilmeni ...
See also:Technetium, Technetium - Notable characteristics, Technetium - Applications, Technetium - Nuclear medicine, Technetium - Industrial, Technetium - History, Technetium - Pre-discovery search, Technetium - Disputed 1925 discovery, Technetium - Official discovery and later history, Technetium - Occurrence and production, Technetium - Part of radioactive waste, Technetium - Reductive immobilization, Technetium - Chemical means, Technetium - Biological means, Technetium - Isotopes, Technetium - Stability of technetium isotopes, Technetium - Precautions Read more here: » Technetium: Encyclopedia II - Technetium - History |
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| | | | | atomic masses: Encyclopedia II - Polonium - Occurrence A very rare element in nature, polonium is found in uranium ores at about 100 micrograms per metric ton (1:1010). Its natural abundance is approximately 0.2% of radium's.
In 1934 an experiment showed that when natural bismuth (Bi-209) is bombarded with neutrons, Bi-210, which is the parent of polonium, was created. Polonium may now be made in milligram amounts in this procedure which uses high ne ...
See also:Polonium, Polonium - Notable characteristics, Polonium - Applications, Polonium - Polonium-210, Polonium - History, Polonium - Occurrence, Polonium - Isotopes, Polonium - Precautions Read more here: » Polonium: Encyclopedia II - Polonium - Occurrence |
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| | | | | atomic masses: Encyclopedia II - Electrolysis - Electrolysis of water One important use of electrolysis is to produce hydrogen. In the future, this could play a central role in shifting our society over to a reliance on hydrogen as an energy carrier for powering electric motors and internal combustion engines. (See hydrogen economy.) Electrolysis of water can be achieved in a simple hands-on project, where electricity from a battery is run into a cup of water. Hydrogen gas will be seen to bubble up at one of the immersed battery probes, and oxygen will bubble at the other.
The energy efficiency o ...
See also:Electrolysis, Electrolysis - Overview, Electrolysis - Electrolysis of water, Electrolysis - Experimenters, Electrolysis - First law of electrolysis, Electrolysis - Second law of electrolysis, Electrolysis - Industrial uses, Electrolysis - Domestic uses, Electrolysis - Military uses Read more here: » Electrolysis: Encyclopedia II - Electrolysis - Electrolysis of water |
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| | | | | atomic masses: Encyclopedia II - Electrolysis - Experimenters Scientific pioneers of electrolysis included:
Humphry Davy
Michael Faraday
Paul Héroult
Svante Arrhenius
Adolph Wilhelm Hermann Kolbe
More recently, electrolysis of heavy water was performed by Fleischmann and Pons in their famous experiment, resulting in anomalous heat generation and the controversial claim of cold fusion.
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See also:Electrolysis, Electrolysis - Overview, Electrolysis - Electrolysis of water, Electrolysis - Experimenters, Electrolysis - First law of electrolysis, Electrolysis - Second law of electrolysis, Electrolysis - Industrial uses, Electrolysis - Domestic uses, Electrolysis - Military uses Read more here: » Electrolysis: Encyclopedia II - Electrolysis - Experimenters |
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| | | | | atomic masses: Encyclopedia II - Electrolysis - Military uses As well as producing hydrogen, electrolysis also produces oxygen. Nuclear submarines are able to generate breathing oxygen from the water around them. This enables submarines to stay underwater for an indefinite period of time.
Space Stations can also use electrolysis to produce extra oxygen from waste water or surplus water produced from the Space Shuttle fuel cells.
Both these applications depend on having an abundant electrical supply, either f ...
See also:Electrolysis, Electrolysis - Overview, Electrolysis - Electrolysis of water, Electrolysis - Experimenters, Electrolysis - First law of electrolysis, Electrolysis - Second law of electrolysis, Electrolysis - Industrial uses, Electrolysis - Domestic uses, Electrolysis - Military uses Read more here: » Electrolysis: Encyclopedia II - Electrolysis - Military uses |
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| | | | | | atomic masses: Encyclopedia II - Caesium - Applications Caesium is most notably used in atomic clocks, which are accurate to seconds in many thousands of years. Since 1967, the International System of Measurements bases its unit of time, the second, on the properties of caesium. SI defines the second as 9,192,631,770 cycles of the radiation which corresponds to the transition between two energy levels of the ground state of the caesium-133 atom.
Cs-134 has been used in hydrology as a measure of caesium output by the nuclear power industry. This isotope is used because, while it is le ...
See also:Caesium, Caesium - Notable characteristics, Caesium - Applications, Caesium - History, Caesium - Occurrence, Caesium - Isotopes, Caesium - Precautions Read more here: » Caesium: Encyclopedia II - Caesium - Applications |
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| | | | | | atomic masses: Encyclopedia II - Nuclear fission - History The results of the bombardment of uranium by neutrons had proved interesting and puzzling. First studied by Enrico Fermi and his colleagues in 1934, they were not properly interpreted until several years later.
On January 16, 1939, Niels Bohr of Copenhagen, Denmark, arrived in the United States to spend several months in Princeton, N. J., and was particularly anxious to discuss some abstract problems with Albert Einstein. (Four years later Bohr was to escape to Sweden from Nazi-occupied Denmark in a small boat, along with thousands of ...
See also:Nuclear fission, Nuclear fission - Physical overview, Nuclear fission - Spontaneous and induced fission; chain reactions, Nuclear fission - Fission reactors, Nuclear fission - Fission bombs, Nuclear fission - History, Nuclear fission - Links Read more here: » Nuclear fission: Encyclopedia II - Nuclear fission - History |
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| | | | | | | atomic masses: Encyclopedia II - Polonium - History Also called Radium F, polonium was discovered by Marie Curie and her husband Pierre Curie in 1898 and was later named after Marie's home land of Poland. Poland at the time was under Russian, Prussian and Austrian domination, and not recognized as an independent country. It was Marie's hope that naming the element after her home land would add notoriety to its plight. Polonium may be the first element named t ...
See also:Polonium, Polonium - Notable characteristics, Polonium - Applications, Polonium - Polonium-210, Polonium - History, Polonium - Occurrence, Polonium - Isotopes, Polonium - Precautions Read more here: » Polonium: Encyclopedia II - Polonium - History |
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| | | | | atomic masses: Encyclopedia II - Thallium - Occurrence Although the metal is reasonably abundant in the Earth's crust at a concentration estimated to be about 0.7 mg/kg, it exists mostly in association with potassium minerals in clays, soils, and granites and, thus, is not generally considered to be commercially recoverable from those forms. The major source of commercial thallium is the trace amounts found in copper, lead, zinc, and other sulfide ores.
Thallium is found in the minerals crookesite (TlCu7Se4), hutchinsonite(TlPbAs5S9), and lorand ...
See also:Thallium, Thallium - Notable characteristics, Thallium - Applications, Thallium - History, Thallium - Occurrence, Thallium - Isotopes, Thallium - Precautions, Thallium - Famous uses Read more here: » Thallium: Encyclopedia II - Thallium - Occurrence |
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| | | | | atomic masses: Encyclopedia II - Periodic table - History The original table was created without a knowledge of the inner structure of atoms: if one orders the elements by atomic mass, and then plots certain other properties against atomic mass, one sees an undulation or periodicity to these properties as a function of atomic mass. The first to recognize these regularities was the German chemist Johann Wolfgang Döbereiner who, in 1829, noticed a number of triads of similar elements:
This was followed by the English chemist John Newlands, who noticed in 1865 that the elements o ...
See also:Periodic table, Periodic table - Groups, Periodic table - Periodicity of chemical properties, Periodic table - Methods for displaying the periodic table, Periodic table - Standard periodic table, Periodic table - Other depictions, Periodic table - Periodic table structure reflects electron configuration, Periodic table - History, Periodic table - Further resources Read more here: » Periodic table: Encyclopedia II - Periodic table - History |
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| | | | | atomic masses: Encyclopedia II - Periodic table - Periodic table structure reflects electron configuration The primary determinant of an element's chemical properties is its electron configuration, particularly the valence shell electrons. For instance, all atoms whose four valence electrons are found on the p shell will behave similarly, regardless of which energy level that last p shell is on. The shell in which the atom's outermost electrons reside determines the "block" to which it belongs. Th ...
See also:Periodic table, Periodic table - Groups, Periodic table - Periodicity of chemical properties, Periodic table - Methods for displaying the periodic table, Periodic table - Standard periodic table, Periodic table - Other depictions, Periodic table - Periodic table structure reflects electron configuration, Periodic table - History, Periodic table - Further resources Read more here: » Periodic table: Encyclopedia II - Periodic table - Periodic table structure reflects electron configuration |
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