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zarkam21 · Answer

Gallium has two naturally occurring isotopes: Ga-69 with a mass of 68.9256 amu and a natural abundance of 60.11%, and Ga-71. Use the atomic mass of gallium from the periodic table to find the mass of Ga-71.

zarkam21 · Answer

I know how to find the atomic weight. But I do not know how to find the missing value to add up to the atomic mass.

zarkam21 · Answer

@Vocaloid When you get a chance.

Vocaloid · Answer

the mass on the periodic table is the weighted-average

so you have

mass of Ga-69 * abundance of Ga-69 + mass of Ga-71 * abundance of Ga-71 = mass on the PT

Vocaloid · Answer

so plugging stuff in

68.9256 amu * 0.6011 + x(1-0.6011) = 69.723

solving for x should give you your sol'n