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The relative Atomic Mass was first proposed by John Dalton in 1803. According to it, the mass of an atom was expressed relative to the mass of one 1H atom. The unit was later changed to 1/16 of the mass of an oxygen atom. However, this measure was discarded when 17O and 18O were discovered. In 1961 the basic unit was changed (once again) to 1/12 of the mass of a 12C atom. The mass of any atom or molecule is measured in atomic mass units (AMU) and the units is defined as 1/12 the mass of a 12Carbon atom.
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What is the two decimal places of relative atomic mass and the molar mass of the element potassium K?
It is 39.10
What To two decimal places what is the relative atomic mass and the molar mass of the element potassium K?
It is 38.96
What is 4.00260 rounded to in atomic mass?
It is 4.0026 : the atomic mass can be a fraction.
What is percent abundance?
Take percent abundance times atomic mass for each isotope then add all up for average atomic mass.
Why are most atomic masses a decimal?
The atomic mass of an isotope of an element is the mass of the nucleons (neutrons + protons) in an atom of that isotope. This is nearly, though not exactly, equal to the number of nucleons, and so is nearly a whole number.The main cause for the atomic mass being fractional is that most elements have numerous isotopes, each with a different number of neutrons and so a different atomic mass. The atomic mass for an element is the average of the atomic masses of all its isotopes, weighted together in the proportion of the isotopes' abundance on earth. It is this weighting together that results in the numbers being fractional.
