Isotopes and Atomic Mass

Calculate the atomic mass for carbon using the following data:

• 15.236 amu

• 12.011 amu

• 14.547 amu

• 10.396

Nitrogen has two isotopes. One has an atomic mass of 14.003 amu and a relative abundance of 99.63% while the other isotope has an atomic mass of 15.000 amu and a relative abundance of 0.37%. What is the average atomic mass for nitrogen?

• 14.107 amu

• 14.407 amu

• 14.007 amu

• 14.907 amu

The atomic mass of the isotope copper-_______ is 62.930 amu.

The atomic mass of magnesium from the Periodic Table is 24.31 amu. What does this mass represent?

• the atomic mass of the most abundant isotope of magnesium

• the weighted average of the two most abundant isotopes of magnesium

• the weighted average of all of the naturally occurring isotopes of magnesium

Most elements occur in nature as a single isotope.

• TRUE

• FALSE

The average atomic mass for an element can be easily calculated by taking the average of the atomic mass units of each isotope.

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• FALSE

Calculations of atomic mass use the percent abundance of each isotope.

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• FALSE

There are 3 naturally occurring isotopes of hydrogen and 2 naturally occurring isotopes of copper.

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• FALSE

63.55 daltons is the formula mass of copper.

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• FALSE

To calculate the atomic mass of an element, the percent abundance of each isotope is needed.

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• FALSE