|
Mirror Nuclei
In physics, mirror nuclei are a pair of isobars of two different elements where the number of protons of isobar one (Z1) equals the number of neutrons of isobar two (N2) and the number of protons of isotope two (Z2) equals the number of neutrons in isotope one (N1); in short: Z1 = N2 and Z2 = N1. This implies that the mass numbers of the isotopes are the same: N1 + Z1 = N2 + Z2. Examples of mirror nuclei include: Pairs of mirror nuclei have the same spin and parity. If we constrain to odd number of nucleons (A=Z+N) then we find mirror nuclei that differ from one another by exchanging a proton by a neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle .... Interesting to observe is their binding energy which is mainly due to the strong interaction and also due to Coulomb inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." It is one of the most fundamental scientific disciplines. "Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isobar (nuclide)
Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number (or number of protons) but have the same mass number. An example of a series of isobars is 40S, 40Cl, 40Ar, 40K, and 40Ca. While the nuclei of these nuclides all contain 40 nucleons, they contain varying numbers of protons and neutrons. The term "isobars" (originally "isobares") for nuclides was suggested by British chemist Alfred Walter Stewart in 1918. It is derived . Mass The same mass number implies neither the same mass of nuclei, nor equal atomic masses of corresponding nuclides. From the Weizsäcker formula for the mass of a nucleus: : m(A,Z) = Z m_p + N m_n - a_ A + a_ A^ + a_ \frac + a_ \frac - \delta(A,Z) where mass number equals to the sum of atomic number and number of neutrons , and , , , , , are constants, one can see that the mass depends on and non-linearly, even for a constant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Element (chemistry)
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its nucleus. Atoms of the same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules. Some elements form molecules of atoms of said element only: e.g. atoms of hydrogen (H) form diatomic molecules (H). Chemical compounds are substances made of atoms of different elements; they can have molecular or non-molecular structure. Mixtures are materials containing different chemical substances; that means (in case of molecular substances) that they contain different types of molecules. Atoms of one element can be transformed into atoms of a different element in nuclear reactions, which change an atom's atomic number. Historically, the term "chemical element" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tritium
Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 (''protium'') contains one proton and no neutrons, and that of non-radioactive hydrogen-2 ('' deuterium'') contains one proton and one neutron. Tritium is the heaviest particle-bound isotope of hydrogen. It is one of the few nuclides with a distinct name. The use of the name hydrogen-3, though more systematic, is much less common. Naturally occurring tritium is extremely rare on Earth. The atmosphere has only trace amounts, formed by the interaction of its gases with cosmic rays. It can be produced artificially by irradiation of lithium or lithium-bearing ceramic pebbles in a nuclear reactor and is a low-abundance byproduct in normal operations of nuclear reactors. Tritium is used as the energy source in radio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with more protons than neutrons. It was discovered in 1939. Helium-3 atoms are fermionic and become a superfluid at the temperature of 2.491 mK. Helium-3 occurs as a primordial nuclide, escaping from Earth's crust into its atmosphere and into outer space over millions of years. It is also thought to be a natural nucleogenic and cosmogenic nuclide, one produced when lithium is bombarded by natural neutrons, which can be released by spontaneous fission and by nuclear reactions with cosmic rays. Some found in the terrestrial atmosphere is a remnant of atmospheric and underwater nuclear weapons testing. Nuclear fusion using helium-3 has long been viewed as a desirable future energy source. The fusion of two of its atoms would be aneut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon-14
Carbon-14, C-14, C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic matter is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples. Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California. Its existence had been suggested by Franz Kurie in 1934. There are three naturally occurring isotopes of carbon on Earth: carbon-12 (C), which makes up 99% of all carbon on Earth; carbon-13 (C), which makes up 1%; and carbon-14 (C), which occurs in trace amounts, making up about 1-1.5 atoms per 10 atoms of carbon in the atmosphere. C and C are both stable; C is unstable, with half-life years. Carbon-14 has a specific activity of 62.4 mCi/mmol (2.31 GBq/mmol), or 164.9 GBq/g. Carbon-14 decay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Oxygen
There are three known stable isotopes of oxygen (8O): , , and . Radioactive isotopes ranging from to have also been characterized, all short-lived. The longest-lived radioisotope is with a half-life of , while the shortest-lived isotope is the unbound with a half-life of , though half-lives have not been measured for the unbound heavy isotopes and . List of isotopes , -id=Oxygen-11 , , style="text-align:right" , 8 , style="text-align:right" , 3 , , [] , proton emission, 2p , , (3/2−) , , , -id=Oxygen-12 , , style="text-align:right" , 8 , style="text-align:right" , 4 , , , 2p , , 0+ , , , - , rowspan=3, , rowspan=3 style="text-align:right" , 8 , rowspan=3 style="text-align:right" , 5 , rowspan=3, , rowspan=3, , β+ () , , rowspan=3, (3/2−) , rowspan=3, , rowspan=3, , - , β+p () , , - , β+p,α ( , - , Can be used in NMR studies of metabolic pathways. , style="text-align:right" , 8 , style="text-align:right ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Nitrogen
Natural nitrogen (7N) consists of two stable isotopes: the vast majority (99.6%) of naturally occurring nitrogen is nitrogen-14, with the remainder being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, along with three nuclear isomers. All of these radioisotopes are short-lived, the longest-lived being nitrogen-13 with a half-life of . All of the others have half-lives shorter than ten seconds, with most of these being below 500 milliseconds. Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of , though the half-life of nitrogen-9 has not been measured exactly. List of isotopes , -id=Nitrogen-9 , , style="text-align:right" , 7 , style="text-align:right" , 2 , , , , -id=Nitrogen-14m , style="text-indent:1em" , , colspan="3" style="text-ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Sodium
There are 20 isotopes of sodium (11Na), ranging from to (except for the still-unknown 36Na and 38Na), and five isomers (two for , and one each for , , and ). is the only stable (and the only primordial) isotope. It is considered a monoisotopic element and it has a standard atomic weight of . Sodium has two radioactive cosmogenic isotopes (, with a half-life of ; and , with a half-life of ). With the exception of those two isotopes, all other isotopes have half-lives under a minute, most under a second. The shortest-lived is the unbound , with a half-life of seconds (although the half-life of the similarly unbound 17Na is not measured). Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable (in the form of Na+ ion) in human blood plasma to . By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed. is a positron-emitting isotope with a remarkably long half-life. It is used to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Aluminium
Aluminium or ''aluminum'' (13Al) has 23 known isotopes from 21Al to 43Al and 4 known isomers. Only 27Al (stable isotope) and 26Al (radioactive isotope, t1/2 = ) occur naturally, however 27Al comprises nearly all natural aluminium. Other than 26Al, all radioisotopes have half-lives under 7 minutes, most under a second. The standard atomic weight is . 26Al is produced from argon in the atmosphere by spallation caused by cosmic-ray protons. Aluminium isotopes have found practical application in dating marine sediments, manganese nodules, glacial ice, quartz in rock exposures, and meteorites. The ratio of 26Al to 10Be has been used to study the role of sediment transport, deposition, and storage, as well as burial times, and erosion, on 105 to 106 year time scales. 26Al has also played a significant role in the study of meteorites. List of isotopes , -id=Aluminium-21 , 21Al , style="text-align:right" , 13 , style="text-align:right" , 8 , 21.0278(13) , >1.1 zs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton
A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one Dalton (unit), dalton, are jointly referred to as ''nucleons'' (particles present in atomic nuclei). One or more protons are present in the Atomic nucleus, nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol ''Z''). Since each chemical element, element is identified by the number of protons in its nucleus, each element has its own atomic number, which determines the number of atomic electrons and consequently the chemical characteristi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron
The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the first self-sustaining nuclear reactor (Chicago Pile-1, 1942) and the first nuclear weapon (Trinity (nuclear test), Trinity, 1945). Neutrons are found, together with a similar number of protons in the atomic nucleus, nuclei of atoms. Atoms of a chemical element that differ only in neutron number are called isotopes. Free neutrons are produced copiously in nuclear fission and nuclear fusion, fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes. Neutron stars, formed from massive collapsing stars, consist of neutrons at the density of atomic nuclei but a total mass more than the Sun. Neutron properties and interactions ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
