The _____ of an element is the average mass of an element's naturally occuring atom, or isotopes, taking into account the _____ of each isotope.

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llltkl | College Teacher | (Level 3) Valedictorian

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The atomic mass of an element is the average mass of an element's naturally occurring atoms, or isotopes, taking into account the relative abundance of each isotope.

 For example, Chlorine has two principal stable isotopes, 35Cl (75.78%) and 37Cl (24.22%), found in the relative proportions of 37.89:12.11, respectively, giving chlorine a standard atomic mass of 35.453 amu. Similarly Carbon 12 has an atomic mass of 12.00 (a special case indeed) and a natural abundance of 0.9893. So nearly 99% of all carbon is carbon 12. There are two heavier isotopes too, carbon 13 and carbon 14. Carbon 13 has an atomic mass of 13.00335 and a natural abundance of 0.0107 (about 1.1%). Carbon 14 has an atomic mass of 14.003 and an abundance of 0.000000000001 (1 part in a trillion). All these contribute to make the accepted atomic mass of carbon 12.011.

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givingiswinning | Student, Grade 10 | (Level 1) Valedictorian

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The atomic mass of an element is the average mass of an element's naturally occurring atoms, or isotopes, taking into account the percentage of each isotope.

 
 
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atyourservice | Student, Grade 11 | (Level 3) Valedictorian

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The atomic mass of an element is the average mass of an element's naturally occurring atoms, or isotopes, taking into account the percentage of each isotope.

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