In the PhET simulation, click on the Mixtures tab. Select Mg from the periodic t
ID: 573617 • Letter: I
Question
In the PhET simulation, click on the Mixtures tab. Select Mg from the periodic table. Drag the colored spheres representing the different isotopes of magnesium into the black background. Notice how the amount of any particular isotope in comparison to the others affects the percent composition and the average atomic mass. In the bottom right-hand corner, click on Nature's Mix to see how the selected element's isotopes appear in nature.
Suppose the given data represent the abundance of isotopes of an element. Calculate the average atomic mass of lead based on the given data and the atomic masses.
Express your answer to four significant figures.
Isotope Atomic mass (amu) Percent abundance Pb-206 205.97 14.1 Pb-207 206.98 15.5 Pb-208 207.98 70.4Explanation / Answer
To calculate the average atomic weight, each exact atomic weight is multiplied by its percent abundance (expressed as a decimal). Then, add the results together and round off to an appropriate number of significant figures.
Average Atomic Mass of Pb = (205.97 x 0.141) + (206.98 x 0.155) + (207.98 x 0.704)
Average Atomic Mass of Pb = 207.54