atomic masses

Nuclear fission (in nuclear physics, simply fission) is a process in which the nucleus of an atom splits into two or more smaller nuclei (fission products) and usually some by-product particles. Hence, fission is a form of elemental transmutation. The by-products include free neutrons, photons (usually gamma rays), and other nuclear fragments such as beta particles and alpha particles. Fission of heavy elements can release substantial amounts of useful energy both ...

Including:

• Nuclear fission - Physical overview
• Nuclear fission - Fission reactors
• Nuclear fission - Fission bombs
• Nuclear fission - History
• Nuclear fission - Links

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Caesium (cesium in the United States) pronounced /ˈsiːziəm/; is a chemical element in the periodic table that has the symbol Cs and atomic number 55. It is a soft silvery-gold alkali metal which is one of at least three metals that are liquid at or near room temperature. This element is most notably used in atomic clocks. The variant spelling cesium is sometimes used, especially in North American English, but caesium is the spelling used by the ...

Including:

• Caesium - Notable characteristics
• Caesium - Applications
• Caesium - History
• Caesium - Occurrence
• Caesium - Isotopes
• Caesium - Precautions

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The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. It is defined to be 1/12 of the mass of one atom of carbon-12. 1 u = 1/NA gram = 1/(1000 NA) kg   (where NA is Avogadro's number) 1 u ≈ 1.66053886 × 10−27 kg See 1 E-27 k ...

Including:

• Atomic mass unit - Measuring relative atomic masses
• Atomic mass unit - History

Read more here: » Atomic mass unit: Encyclopedia - Atomic mass unit

Since technetium is unstable, only minute traces occur naturally in the Earth's crust as a spontaneous fission product of uranium. In 1999 David Curtis (see above) estimated that a kilogram of uranium contains 1 nanogram (1×10−9 g) of technetium. Extraterrestrial technetium was found in some red giant stars (S-, M-, and N-types) that contain an absorption line in their spectrum indicating the presence of this element. In contrast with the rare natural occurrence, bulk quantities of technetium-99 are produced each year fr ...

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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 - Occurrence and production

An ionic compound is dissolved with an appropriate solvent, or otherwise melted by heat, so that its ions are available in the liquid. An electrical current is applied between a pair of metal electrodes immersed in the liquid. The negatively charged electrode is called the cathode, and the positively charged one the anode. Each electrode attracts ions which are of the opposite charge. Therefore, positively charged ions (called cations) move towards the cathode, while negatively charged ions (termed anions) move toward the anode. The energy r ...

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Electrolysis, Electrolysis - Overview, Electrolysis - Electrolysis of water, Electrolysis - Experimenters, Electrolysis - First law of electrolysis, Electrolysis - Second law of electrolysis, Electrolysis - Industrial uses, Electrolysis - Military uses

Read more here: » Electrolysis: Encyclopedia II - Electrolysis - Overview

A group, also known as a family, is a vertical column in the periodic table of the elements. There are 18 groups or families in the standard periodic table. Elements in a group have similar configurations of their valence shell electrons, which gives them similar properties. There are three systems of group numbers; one using Hindu-Arabic numerals (1, 2, ... 18), another using Roman numerals (I, II, ... VIII), and one using a combination of Roman numerals and Latin letters (IA, IIA, IB, ... VIIIA). The Roman numeral names are the orig ...

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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

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When it is mixed or alloyed with beryllium, polonium can be a neutron source. Other uses; This element has also been used in devices that eliminate static charges in textile mills and other places. However, beta sources are more commonly used and are less dangerous. Polonium is used on brushes that remove accumulated dust from photographic films. The polonium in these brushes is sealed and controlled thus minimizing radiation hazards. ...

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Polonium, Polonium - Notable characteristics, Polonium - Applications, Polonium - Polonium-210, Polonium - History, Polonium - Occurrence, Polonium - Isotopes, Polonium - Precautions

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In a neutral atom, the number of electrons equals the number of protons. Thus, different isotopes of a given element also have the same number of electrons and the same electronic structure. Because the chemical behavior of an atom is largely determined by its electronic structure, isotopes exhibit nearly identical chemical behavior. The primary exception is that, due to their larger masses, heavier isotopes tend to react somewhat more slowly than lighter isotopes of the s ...

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Isotope, Isotope - Variation in properties between isotopes, Isotope - Occurrence in nature, Isotope - Applications of isotopes, Isotope - Use of chemical properties, Isotope - Use of nuclear properties

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Tellurium is a relatively rare element, in the same chemical family as oxygen, sulfur, selenium, and polonium (the chalcogens). When crystalline, tellurium is silvery-white and when it is in its pure state it has a metallic luster. This is a brittle and easily pulverized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous or telluric acid (Te(OH)6). However, there is some debate whether this form is really amorphous or made of minute crystals. Tellurium is a p-type semiconductor that shows a greater conductivity in ...

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Tellurium, Tellurium - Notable characteristics, Tellurium - Applications, Tellurium - History, Tellurium - Occurrence, Tellurium - Compounds, Tellurium - Isotopes, Tellurium - Precautions

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The odorless and tasteless thallium sulfate was widely used in the past as a rat poison and ant killer. In the United States and many other countries this use is no longer allowed due to safety concerns. Other uses: thallium sulfide's electrical conductivity changes with exposure to infrared light therefore making this compound useful in photocells. thallium bromide-iodide crystals have been used as infrared optical materials. thallium oxide has been used to manufacture glasses that have a high index of refract ...

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Thallium, Thallium - Notable characteristics, Thallium - Applications, Thallium - History, Thallium - Occurrence, Thallium - Isotopes, Thallium - Precautions, Thallium - Famous uses

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The electromagnetic spectrum of caesium has two bright lines in the blue part of the spectrum along with several other lines in the red, yellow, and green. This metal is silvery gold in color and is both soft and ductile. Caesium is also the most electropositive and most alkaline of the stable chemical elements and also has the least ionization potential of all the elements, except for francium. Caesium is the least abundant of the five non-radioactive alkali metals. (Technically, francium is the least common alkali metal, but since it is highly radioactive with less than 30 grams in the entire earth at one time, its ab ...

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Caesium, Caesium - Notable characteristics, Caesium - Applications, Caesium - History, Caesium - Occurrence, Caesium - Isotopes, Caesium - Precautions

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The relative atomic mass is measured with a mass spectrometer. After placing a sample of the element to be measured in the mass spectrometer it is bombarded with electrons which turns the atoms into positive ions. An electric field is then used to accelerate these positive ions, after which the ions are deflected using a magnetic field. As a result the various isotopes are separated out due to the ions of lighter isotopes being deflected more than those heavier. This produces a mass spectrum. This spectrum provides two things: Relative iso ...

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Atomic mass unit, Atomic mass unit - Measuring relative atomic masses, Atomic mass unit - History

Read more here: » Atomic mass unit: Encyclopedia II - Atomic mass unit - Measuring relative atomic masses

Nuclear fission differs from other forms of radioactive decay in that it can be harnessed and controlled via a chain reaction: free neutrons released by each fission event can trigger yet more events, which in turn release more neutrons and cause more fissions. Chemical isotopes that can sustain a fission chain reaction are called nuclear fuels, and are said to be fissile. The most common nuclear fuels are 235U (the isotope of uranium with an atomic mass of 235) and 239Pu (the isotope of plutonium with an atomic mass of ...

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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

Read more here: » Nuclear fission: Encyclopedia II - Nuclear fission - Physical overview

The noble gases were previously referred to as inert gases, but this term is not strictly accurate because several of them do take part in chemical reactions. Another older term was rare gases, although in fact argon forms a considerable part (0.93% by volume, 1.29% by mass) of the Earth's atmosphere. The name 'noble gases' is an allusion to the similarly unreactive Noble metals, so called due to their preciousness, resistance to corrosion and ...

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Noble gas, Noble gas - Etymology, Noble gas - Chemistry, Noble gas - Applications, Noble gas - Physical Properties

Read more here: » Noble gas: Encyclopedia II - Noble gas - Etymology

An ionic compound is dissolved with an appropriate solvent, or otherwise melted by heat, so that its ions are available in the liquid. An electrical current is applied between a pair of metal electrodes immersed in the liquid. The negatively charged electrode is called the cathode, and the positively charged one the anode. Each electrode attracts ions which are of the opposite charge. Therefore, positively charged ions (called cations) move towards the cathode, while negatively charged ions (termed anions) move toward the anode. The energy r ...

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 - Overview

Tellurium (Latin tellus meaning "earth") was discovered in 1782 by the Hungarian Franz-Joseph Müller von Reichenstein (Müller Ferenc) in Transylvania. In 1798 it was named by Martin Heinrich Klaproth who earlier isolated it. The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining steel, which became the dominant use. ...

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Tellurium, Tellurium - Notable characteristics, Tellurium - Applications, Tellurium - History, Tellurium - Occurrence, Tellurium - Compounds, Tellurium - Isotopes, Tellurium - Precautions

Read more here: » Tellurium: Encyclopedia II - Tellurium - History

Technetium - Chemical means. The pertechnetate ion (TcO4-) could find use as an anodic corrosion inhibitor for steel (this possible use is hindered by technetium's radioactivity). The pertechnetate reacts with the steel surface to form a layer of technetium dioxide which prevents further corrosion, this formation of technetium dioxide explains how iron powder can be used to remove pertechnetate from water. As an alternative activated carbon can be used to remove pertechnetate from water. ...

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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 - Reductive immobilization

Technetium is one of three elements in the first 82 that have no stable isotopes (the other such elements are promethium and tungsten (although because the half-life of tungsten is so long (2.09E19 y), tungsten is usually classed as being stable). The most stable radioisotopes are Tc-98 with a half-life of 4.2 million years, Tc-97 (half-life: 2.6 million years) and Tc-99 (half-life: 211,100 years). Twenty-two other radioisotopes have been characterized with atomic masses ranging from 87.933 u (Tc-88) to 112.931 u (Tc-113). Most of the ...

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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 - Isotopes

Tellurium is sometimes found in its native form, but is more often found as the telluride of gold (calaverite), and combined with other metals. The principal source of tellurium is from anode sludges produced during the electrolytic refining of blister copper. It is a component of dusts from blast furnace refining of lead. Tellurium is produced mainly in the US, Canada, Peru, and Japan. Commercial-grade tellurium, which is not toxic, is usually marketed as minus 200-mesh powder but is also available as slabs, ingots, sticks, or lumps. The yearend price for tellurium in 2000 was US$ 14 per pound. ...

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Tellurium, Tellurium - Notable characteristics, Tellurium - Applications, Tellurium - History, Tellurium - Occurrence, Tellurium - Compounds, Tellurium - Isotopes, Tellurium - Precautions

Read more here: » Tellurium: Encyclopedia II - Tellurium - Occurrence

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, New Jersey, 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 thousan ...

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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

Read more here: » Nuclear fission: Encyclopedia II - Nuclear fission - History