Atomic Mass

Front

What is atomic mass?

Back

The weighted average mass of an element's isotopes, measured in atomic mass units (amu).

Front

What is an isotope?

Back

Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Front

How is the average atomic mass calculated?

Back

By multiplying the mass of each isotope by its relative abundance (as a decimal), then summing these values.

Front

What does relative abundance mean?

Back

The percentage of a particular isotope present in a naturally occurring sample of an element.

Front

If an element has two isotopes, one with a mass of 10 amu and 40% abundance, and another with 12 amu and 60% abundance, what is the average atomic mass?

Back

11.2 amu.

Front

What is the significance of atomic mass in the periodic table?

Back

It helps to identify the element and predict its behavior in chemical reactions.

Front

Which isotope of chlorine is more abundant if the atomic mass is 35.45?

Back

Cl-35.

Front

What is the average atomic mass of an element with isotopes of 15.0 amu (30% abundance) and 16.0 amu (70% abundance)?

Back

15.7 amu.

Front

What is the average atomic mass of lead if it has isotopes of lead-204, lead-206, lead-207, and lead-208, with an average atomic mass of 207.2?

Back

Lead-207 is likely the most abundant.

Front

What is the average atomic mass of silver?

Back

107.8677 amu.