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  2. Standard atomic weight - Wikipedia

    en.wikipedia.org/wiki/Standard_atomic_weight

    The standard atomic weight (A r °(Cu)) for copper is the average, weighted by their natural abundance, and then divided by the atomic mass constant m u. [ 1 ] The standard atomic weight of a chemical element (symbol A r °(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element ...

  3. Mass fraction (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Mass_fraction_(chemistry)

    Mass fraction can also be expressed, with a denominator of 100, as percentage by mass (in commercial contexts often called percentage by weight, abbreviated wt.% or % w/w; see mass versus weight). It is one way of expressing the composition of a mixture in a dimensionless size ; mole fraction (percentage by moles , mol%) and volume fraction ...

  4. Template:Chem molar mass - Wikipedia

    en.wikipedia.org/wiki/Template:Chem_molar_mass

    Atomic number Element Molar mass Formal standard atomic weight s.a.w., formal short Note Z calculated; g·mol −1 A r, standard [2] A r, abridged and conventional [2] C 9 H 8 O 4: 180.159 g·mol −1: aspirin, calculated from formula C 9 H 8 O 4: 180.157 g·mol −1: fixed value from ... |charge=+1: −0.000 548 579 909 070 g·mol −1 |charge ...

  5. Molar mass - Wikipedia

    en.wikipedia.org/wiki/Molar_mass

    The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [2] or the conventional atomic weight.

  6. Mass balance - Wikipedia

    en.wikipedia.org/wiki/Mass_balance

    Strictly speaking the above equation holds also for systems with chemical reactions if the terms in the balance equation are taken to refer to total mass, i.e. the sum of all the chemical species of the system. In the absence of a chemical reaction the amount of any chemical species flowing in and out will be the same; this gives rise to an ...

  7. Atomic mass - Wikipedia

    en.wikipedia.org/wiki/Atomic_mass

    As such, relative atomic mass and standard atomic weight often differ numerically from the relative isotopic mass. The atomic mass (relative isotopic mass) is defined as the mass of a single atom, which can only be one isotope (nuclide) at a time, and is not an abundance-weighted average, as in the case of relative atomic mass/atomic weight ...

  8. Electron mass - Wikipedia

    en.wikipedia.org/wiki/Electron_mass

    The electron relative atomic mass also enters into the calculation of all other relative atomic masses. By convention, relative atomic masses are quoted for neutral atoms, but the actual measurements are made on positive ions, either in a mass spectrometer or a Penning trap. Hence the mass of the electrons must be added back on to the measured ...

  9. Semi-empirical mass formula - Wikipedia

    en.wikipedia.org/wiki/Semi-empirical_mass_formula

    In nuclear physics, the semi-empirical mass formula (SEMF) (sometimes also called the Weizsäcker formula, Bethe–Weizsäcker formula, or Bethe–Weizsäcker mass formula to distinguish it from the Bethe–Weizsäcker process) is used to approximate the mass of an atomic nucleus from its number of protons and neutrons.