An elements had three isotopes, determine the average atomic mass and element.
1x - percent abundance = 80%, mass = 127
2x - percent abundance = 17%, mass = 126
3x - percent abundance = 3% , mass = 128

126.86

Explanation:

Given parameters:

1x - percent abundance = 80%(0.8), mass = 127

2x - percent abundance = 17%(0.17), mass = 126

3x - percent abundance = 3%(0.03) , mass = 128

Unknown:

Average atomic mass = ?

Solution:

The average atomic mass is the average of all isotopes of element. It can be calculated using the expression below;

RAM  = (mass x abundance of 1x) + (mass x abundance of 2x) + (mass x abundance of 3x)

Now insert the parameters and solve;

RAM = (127 x 0.8) + (126 x 0.17) + (128 x 0.03)  = 126.86

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