Average Atomic Mass

An element has three isotopes. Given the abundances and relative masses, calculate the average atomic mass and determine (from the periodic table) which element it is.

Abundances | Relative masses

0.005% | 234.04 amu

0.720% | 235.04 amu

99.275% | 238.05 amu

What is the average atomic mass for thallium, Tl, if there are two isotopes with the following masses and abundances? Tl-203 has a mass of 203 amu with an abundance of 29.5 % Tl-205 has a mass of 205 amu with an abundance of 70.5 %

A sample of cesium is 75% Cs-133, 20% Cs-132, and 5% Cs-134. What is the average atomic mass?

A meteor crashes to Earth, is collected and analyzed. To everyone’s surprise, a new element is discovered with an atomic number of 120. Calculate the weight-average atomic mass for this new element, Ubn (Unbinnulium). Show all work below.

Element Q is an unknown element. Q has abundance of 90.51%, Q has abundance of 0.21%, and Q has abundance of 9.22%. Find the average atomic mass of Q and identify the unknown element.

An element with 4.35% have a mass of 49.9461 amu, 83.79% have amass of 51.9405 amu, 9.50% have a mass of 52.9407 amu, and 2.36% have a mass of 53.9389amu.

Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208.  The average atomic mass of lead is 207.2.  Which isotope of lead is likely to be the most abundant.

An element has two isotopes with masses of 10 amu and 11 amu. If the abundance of the 10 amu isotope is 20% and the 11 amu isotope is 80%, what is the average atomic mass of the element?

The average atomic mass of chlorine is 35.5 amu. If chlorine has two isotopes, Cl-35 and Cl-37, which isotope is more abundant?

An element X has three isotopes with the following abundances and masses: 5% of 50 amu, 15% of 51 amu, and 80% of 52 amu. Calculate the average atomic mass of element X.