Relative atomic mass of an element ?

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Discussion Overview

The discussion revolves around calculating the relative atomic mass of neon based on the percentages of its isotopes. It includes a mathematical approach to the problem and addresses the concept of why relative atomic masses are not whole numbers.

Discussion Character

  • Homework-related, Mathematical reasoning, Conceptual clarification

Main Points Raised

  • One participant presents a calculation for the relative atomic mass of neon based on the isotopic composition but is unsure about the division step.
  • Another participant suggests dividing the sum by 100 to obtain the correct relative atomic mass.
  • A third participant confirms their calculation of 20.16 after applying the suggested method.
  • There is a question about why relative atomic masses are not whole numbers, with a suggestion that it is due to the presence of isotopes.

Areas of Agreement / Disagreement

Participants generally agree on the method for calculating the relative atomic mass and the reason for non-whole number values, but there is no explicit consensus on the initial calculation method.

Contextual Notes

Some calculations depend on the correct application of percentages, and there is a lack of clarity on the initial approach to the problem.

faisal
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relative atomic mass of an element ?

A sample of neon was found to cotain 90.9% of 20Ne, 0.26% of 21Ne, & 8.8% of 22Ne, Calculate the relative atomic mass of neon.
this is what i'v done so far (90.9x 20)+ (0.26x21)+(8.8x22)= 2017/?
i don't know what to divide it by :confused: ? I'm not given a mass spectra?
P.s.
why r relative atomic masses for some elements not whole numbers, is it because they r isotopes?
 
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Divide by 100.

That will get you 20.17

Yes, they are not whole numbers because of isotopes. That's what you're taking account for by finding the relative atomic mass.
 
Thanx, i did the question again and i got 20.16 this is what i did (90.9/100x20)+(0.26/100x21)+(8.8/100x22)= 20.16
 
Either way works. :)
 

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