Calculating Average Atomic Mass

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Presentation transcript:

Calculating Average Atomic Mass Atomic Structure Calculating Average Atomic Mass

Mass of isotope (Relative Atomic Mass) Average Atomic Mass Weight underneath each element on the periodic table is an average of all the isotopes that exist for that specific element 1 H 1.0079 Hydrogen Isotopes of Hydrogen Mass of isotope (Relative Atomic Mass) Percent Abundance (%) Hydrogen – 1 1.007825 99.9885 Hydrogen – 2 2.0141022 0.0115 Hydrogen – 3 3.016049 0.003

Which isotope of Hydrogen is most abundant? Isotopes of Hydrogen Mass of isotope (Relative Atomic Mass) Percent Abundance (%) Hydrogen – 1 1.007825 99.9885 Hydrogen – 2 2.0141022 0.0115 Hydrogen – 3 3.016049 0.003 The isotope whose mass is closest to the average atomic mass is the most abundant.

Which isotope is more abundant given the average atomic mass of Practice questions Which isotope is more abundant given the average atomic mass of Carbon is 12.011, C-14 or C-12?

Calculating Average Atomic Mass Convert Percentages into DECIMALS These percentages are your percent abundance #’s To do this you need to Divide by 100 Multiply the percent abundance DECIMALS by its relative atomic mass Add ALL the numbers from STEP 2 together

These percentages are your percent abundance #’s 1. Convert Percentages into DECIMALS These percentages are your percent abundance #’s (Divide by 100) 2. Multiply the percent abundance DECIMALS by its relative atomic mass 3. Add ALL the numbers from STEP 2 together Naturally occurring copper is 69.1% Cu-63 and 30.9% Cu-65. What is the average atomic mass?

These percentages are your percent abundance #’s 1. Convert Percentages into DECIMALS These percentages are your percent abundance #’s (Divide by 100) 2. Multiply the percent abundance DECIMALS by its relative atomic mass 3. Add ALL the numbers from STEP 2 together What is the average atomic mass of a sample of Neon with 90.0% Neon-20 & 10.0%Neon-22?

These percentages are your percent abundance #’s 1. Convert Percentages into DECIMALS These percentages are your percent abundance #’s (Divide by 100) 2. Multiply the percent abundance DECIMALS by its relative atomic mass 3. Add ALL the numbers from STEP 2 together Calculate the average atomic weight for carbon from the following isotopic information: 98.892% Carbon-12 (exact mass 12.00) and 1.108% Carbon-13 (exact mass 13.0034)