The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply. The percentage of an element produced in the top producing country. Low = substitution is possible with little or no economic and/or performance impact Medium = substitution is possible but there may be an economic and/or performance impact High = substitution not possible or very difficult. The availability of suitable substitutes for a given commodity. A higher recycling rate may reduce risk to supply. The percentage of a commodity which is recycled. The number of atoms of the element per 1 million atoms of the Earth’s crust. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.ĭata for this section been provided by the British Geological Survey.Īn integrated supply risk index from 1 (very low risk) to 10 (very high risk). Where more than one isotope exists, the value given is the abundance weighted average.Ītoms of the same element with different numbers of neutrons. This is approximately the sum of the number of protons and neutrons in the nucleus. The mass of an atom relative to that of carbon-12. The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.ĭensity is the mass of a substance that would fill 1 cm 3 at room temperature. The temperature at which the liquid–gas phase change occurs. The temperature at which the solid–liquid phase change occurs. The arrangements of electrons above the last (closed shell) noble gas. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f). The atomic number of each element increases by one, reading from left to right.Įlements are organised into blocks by the orbital type in which the outer electrons are found. Members of a group typically have similar properties and electron configurations in their outer shell.Ī horizontal row in the periodic table. (2003), "Atomic Weights of the Elements: Review 2000", Pure and Applied Chemistry, 75 (6): 683–800, doi: 10.A vertical column in the periodic table. "Spectrometry of the Neutrino Recoils of Argon-37". The Physical Universe: An Introduction to Astronomy. This heavier isotope tends to be more prevalent in chloride minerals than in aqueous solutions such as sea water, although the isotopic composition of organochlorine compounds can vary in either direction from the SMOC standard in the range of several parts per thousand. There is a known variation in the isotopic abundance of chlorine-37. SMOC is known to be around 24.219% chlorine-37 and to have an atomic weight of around 35.4525 When measuring deviations in isotopic composition, the usual reference point is "Standard Mean Ocean Chloride" (SMOC), although a NIST Standard Reference Material (975a) also exists. The representative terrestrial abundance of chlorine-37 is 24.22(4)% of chlorine atoms, with a normal range of 24.14–24.36% of chlorine atoms. Detection methods involve several hundred thousand liters of carbon tetrachloride (CCl 4) or tetrachloroethylene (C 2Cl 4) stored in underground tanks. The detection of these electrons confirms that a neutrino event took place. These last reactions involve Auger electrons of specific energies. Chlorine-37 transmutes into argon-37 via the reaction 37Īrgon-37 then de-excites itself via electron capture (half-life = 35 d) into chlorine-37 via the reaction One of the historically important radiochemical methods of solar neutrino detection is based on inverse electron capture triggered by the absorption of an electron neutrino.
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