(Solved) How is the ?average? in atomic mass determined and what is the difference between the atomic mass and the atom?

bugel2000

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11 years ago

How is the ?average? in atomic mass determined and what is the difference between the atomic mass and the atom?

How is the ?average? in atomic mass determined and what is the difference between the atomic mass and the atomic number.

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bugaboo5

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11 years ago

What scientists do to find the average is take the mass of all the known isotopes and average them out.
The atomic mass is the number of protons + the number of neutrons.

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tomtom1

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11 years ago

atomic number = # of protons
Mass = Average mass of protons and Neutrons in AMU (ex. the atom He with 2 protons. If it had a mass of 6 there would be 4 neutrons and 2 protons.
Average mass is found by = taking the percentage of istopes of a certain atom and finding the average. (ex. there may be 80% atoms of hydrogen with a mass of 1, but there is still that other small percentage which has an extra neutron making the mass raise to two, and more percentages with different masses, making the atomic mass 1.11111 or something)

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ton

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11 years ago

This verified answer contains over 210 words.

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finnykev

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11 years ago

The average atomic mass is a "weighted" average. Since most elements have different amounts of isotopes you have to factor in the amount of each isotope.
For example chlorine has two common isotopes Cl-35 and Cl-37. Most people would say the average is 36. However 75% of any chlorine sample is Cl-35, and 25% is Cl-37. So the weighted average is:
0.75(35) + 0.25(37) = 35.5 amu.
Atomic mass is the SUM of the protons and the neutrons where as the atomic number is just the number of protons.

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