Use the information for the isotopes of X to calculate the average atomic mass of X, and identify the element.
HELP. I don't remember learning this and my teacher said it'll be on my final exam.

Question

Use the information for the isotopes of X to calculate the average atomic mass of X, and identify the element.
HELP. I don't remember learning this and my teacher said it'll be on my final exam.

anonymous · Answer

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jfraser · Answer

each isotope contributes a portion of its weight to the average, but it's not a straight average. It's a $weighted$ average. The total average mass will be equal to the sum of the $percentages$ of each weight

jfraser · Answer

the general equation will look like this:$$avg.weight = (weight \space of \space X)*(fraction \space of \space X) + (weight \space of \space Y)*(fraction \space of \space Y)$$

jfraser · Answer

to turn the percentages into fractions, divide by 100 to get rid of the percent, so 6.5% as a fraction is 0.065