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Basic Atomic and Nuclear Physics
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Both the terms relative atomic mass and atomic weight are often loosely used to refer to a standard atomic weight. The elemental standard atomic weight is the average mass of the atoms in a normal sample of the element to 1/12 the mass of an atom of 12C. A normal sample is one from any reasonable source of the element or its compounds used in commerce for industry and one that has not undergone significant isotopic modification. These values are widely published in books and on wall charts of the Periodic Table.
Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
susceptibility increases with temperature up to a critical value, the Néel temperature, above which the material becomes paramagnetic. Antiparticle - A particle having the same mass as a given elementary particle and a charge equal in magnitude but opposite in sign. Appearance potential* - The lowest energy which must be imparted to the parent molecule to cause it to produce a particular specified parent ion. This energy, usually stated in eV, may be imparted by electron impact, photon impact, or in other ways. More properly called appearance energy. [3] Appearance potential spectroscopy (APS) - See Techniques for Materials Characterization, page 12-1. Are (a) - A unit of area equal to 100 m2. [1] Arenes - Monocyclic and polycyclic aromatic hydrocarbons. See aromatic compounds. [5] Aromatic compounds - Compounds whose structure includes a cyclic delocalized -electron system. Historical use of the term implies a ring containing only carbon (e.g., benzene, naphthalene), but it is often generalized to include heterocyclic structures such as pyridine and thiophene. [5] Arrhenius equation - A key equation in chemical kinetics which expresses the rate constant k as k = Aexp(-Ea/RT), where Ea is the activation energy, R the molar gas constant, and T the temperature. A is called the preexponential factor and, for simple gas phase reactions, may be identified with the collision frequency. Arsines - AsH3 and compounds derived from it by substituting one, two or three hydrogen atoms by hydrocarbyl groups. RAsH2, R2AsH, R3As (R not equal to H) are called primary, secondary and tertiary arsines, respectively. [5] Aryl groups - Groups derived from arenes by removal of a hydrogen atom from a ring carbon atom. Groups similarly derived from heteroarenes are sometimes subsumed in this definition. [5] Astronomical unit (AU)* - The mean distance of the earth from the sun, equal to 1.49597870 × 1011 m. Atomic absorption spectroscopy (AAS) - See Techniques for Materials Characterization, page 12-1. Atomic emission spectroscopy (AES) - See Techniques for Materials Characterization, page 12-1. Atomic force microscopy (AFM) - See Techniques for Materials Characterization, page 12-1. Atomic mass* - The mass of a nuclide, normally expressed in unified atomic mass units (u). Atomic mass unit (u)* - A unit of mass used in atomic, molecular, and nuclear science, defined as the mass of one atom of 12C divided by 12. Its approximate value is 1.66054 × 10-27 kg. Also called the unified atomic mass unit. [1] Atomic number (Z) - A characteristic property of an element, equal to the number of protons in the nucleus. Atomic weight (Ar)* - The ratio of the average mass per atom of an element to 1/12 of the mass of nuclide 12C. An atomic weight can be defined for a sample of any given isotopic composition. The standard atomic weight refers to a sample of normal terrestrial isotopic composition. The term relative atomic mass is synonymous with atomic weight. [2] Attenuated total reflection (ATR) - See Techniques for Materials Characterization, page 12-1.
Using simple algebraic concepts to understand chemical composition problems
Published in International Journal of Mathematical Education in Science and Technology, 2022
Enrico Ravera, Claudio Luchinat
1.0000 g of a mixture of copper(II) oxide, CuO and copper(I) oxide, CuO is reduced through a stream of hydrogen. 0.8346 g of elementary copper are obtained. Find the per cent composition of the mixture. The standard atomic weight of copper is taken to be , whereas that of oxygen is taken to be . The last digit of the masses is assumed to be affected by uncertainty. [The data were generated assuming the weight of the two components to be 0.600 and 0.400, respectively.]