Answer:
6.94 amu
Explanation:
The average atomic mass of an element can be calculated from the addition mass of their isotopes.
For the exercise you should follow these steps:
1) Change the percentages to fraction, just need to divide by 100.
To avoid confusions and to keep all the information organize, you can make a table like this:
Abundance
% fraction (divide by 100)
92.4 0.924
7.60 0.076
total100.0 1.000
***You can move the decimal point two places to the left.
As you can see in the table, when you add percentages the result is equal to 100, but when you sum fractions the result is equal to 1.
Now multiply the mass with their respective fraction:
0.924 (7.016 amu) = 6.483 amu
0.076 (6.015 amu) = 0.457 amu
The final table will be:
% fraction mass amu mass amu
92.4 0.924 7.016 6.483
7.60 0.076 6.015 0.457
total100.0 1.000 Average 6.940
The average atomis mass of this element is 6.94 amu
You can make this type of tables and do the calculations in excel, check the table that I attached.
