Hafnium has six naturally occurring isotopes: 0.16% of 174hf, with an atomic weight of 173.940 amu; 5.26% of 176hf, with an atomic weight of 175.941 amu; 18.60% of 177hf, with an atomic weight of 176.943 amu; 27.28% of 178hf, with an atomic weight of 177.944 amu; 13.62% of 179hf, with an atomic weight of 178.946 amu; . and 35.08% of 180hf, with an atomic weight of 179.947 amu. calculate the average atomic weight of hf. give your answer to three decimal places.

177.277amu

Explanation:

the total occuring isotopes for Hafnium is =6.

First isotope had an atomic weight of 173.940amu

Second isotope =175.941amu

Third isotope =176.943amu

Fourth isotope=177.944amu

Fifth isotope. =178.946amu

sixth isotope .179.947amu

Average atomic weight of Hafnium= sum of all the atomic weights of the isotopes/ Total occuring isotopes

Thus, 173.940amu+175.941amu+176.943amu+177.944amu+178.946amu+179.947amu.= 1063.661amu

Average atomic weight= 1063.661amu /6 = 177.2768333amu

= 177.277amu to 3 decimal places.

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