Isotopes and Average Atomic Mass

Flashcards covering isotopes, average atomic mass, and calculations based on lecture notes.

What are isotopes?

Isotopes are versions of an element with different masses.

How do isotopes of an element differ from each other?

Isotopes have different numbers of neutrons.

What do isotopes of the same element have in common?

Isotopes have the same number of protons.

How is the average mass listed on the periodic table determined?

It is a weighted average of all isotopes of that element.

How does the abundance of an isotope influence the average atomic mass on the periodic table?

More common isotopes affect the average more, meaning the average atomic mass will be closest to the mass of the most common isotope.

If the average atomic mass for Magnesium is approximately 24.305 amu, which isotope is the most common among 24Mg, 25Mg, or 26Mg?

24Mg.

What does it indicate if an element only has one stable isotope regarding its atomic mass on the periodic table?

The atomic mass listed on the periodic table will simply be the mass of that single isotope.

What is the formula for calculating the average atomic mass of an element?

Average Atomic Mass = f1M1 + f2M2 + …

In the average atomic mass formula (a.a.m. = f1M1 + f2M2 + …), what do 'f' and 'M' represent?

'f' represents the fractional abundance (percent abundance divided by 100), and 'M' represents the mass of each isotope.

Given Chlorine-35 (mass 34.97 amu, 76% abundant) and Chlorine-37 (mass 36.97 amu, 24% abundant), what is the calculated average atomic mass of Chlorine?

35.45 amu.

Calculate the average atomic mass of Lithium if Lithium-6 is 7.59% abundant (6.015 amu) and Lithium-7 is 92.41% abundant (7.016 amu).

6.940 amu.

What is the average atomic mass of Silicon given Silicon-28 (92.2% abundant, 27.98 amu), Silicon-29 (4.7% abundant, 28.98 amu), and Silicon-30 (3.1% abundant, 29.97 amu)?

28.09 amu.