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2. Mass number - Wikipedia

   en.wikipedia.org/wiki/Mass_number

   The mass number should also not be confused with the standard atomic weight (also called atomic weight) of an element, which is the ratio of the average atomic mass of the different isotopes of that element (weighted by abundance) to the atomic mass constant. [9] The atomic weight is a mass ratio, while the mass number is a counted number (and ...

3. Atomic mass - Wikipedia

   en.wikipedia.org/wiki/Atomic_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. The atomic mass or relative isotopic mass of each isotope and nuclide of a chemical element is, therefore, a number ...

4. List of physical constants - Wikipedia

   en.wikipedia.org/wiki/List_of_physical_constants

   For example, the atomic mass constant is exactly known when expressed using the dalton (its value is exactly 1 Da), but the kilogram is not exactly known when using these units, the opposite of when expressing the same quantities using the kilogram.

5. Orders of magnitude (mass) - Wikipedia

   en.wikipedia.org/wiki/Orders_of_magnitude_(mass)

   The table at right is based on the kilogram (kg), the base unit of mass in the International System of Units . The kilogram is the only standard unit to include an SI prefix (kilo-) as part of its name. The gram (10 −3 kg) is an SI derived unit of mass.

6. Template:Atomic mass - Wikipedia

   en.wikipedia.org/wiki/Template:Atomic_mass

   The mass of an atom or a molecule is referred to as the atomic mass. The atomic mass is used to find the average mass of elements and molecules and to solve stoichiometry problems. The name "atomic mass" is used for historical reasons, and originates from the fact that chemistry was the first science to investigate the same physical objects on ...

7. Dalton (unit) - Wikipedia

   en.wikipedia.org/wiki/Dalton_(unit)

   In 1803 John Dalton proposed to use the (still unknown) atomic mass of the lightest atom, hydrogen, as the natural unit of atomic mass. This was the basis of the atomic weight scale. [12] For technical reasons, in 1898, chemist Wilhelm Ostwald and others proposed to redefine the unit of atomic mass as ⁠ 1 / 16 ⁠ the mass of an oxygen atom. [13]

8. 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 ...

9. Electron mass - Wikipedia

   en.wikipedia.org/wiki/Electron_mass

   In particle physics, the electron mass (symbol: m e) is the mass of a stationary electron, also known as the invariant mass of the electron. It is one of the fundamental constants of physics . It has a value of about 9.109 × 10 −31 kilograms or about 5.486 × 10 −4 daltons , which has an energy-equivalent of about 8.187 × 10 −14 joules ...