Question

Strontium has 4 known isotopes: strontium-84, strontium-86, strontium-87, and strontium-88. The known average atomic mass of strontium is 87.62 u. Predict which of the following isotopes has the highest percent abundance. Defend your answer.

Answer 1

To predict which of the four isotopes of strontium has the highest percent abundance, we can use the information about the average atomic mass.

The average atomic mass of an element is a weighted average of the masses of its isotopes, taking into account their percent abundances. We can set up an equation using the given average atomic mass (87.62 u) and the masses of the four isotopes to solve for the percent abundances:

Average Atomic Mass = (Mass of Isotope 1 × Percent Abundance of Isotope 1) + (Mass of Isotope 2 × Percent Abundance of Isotope 2) + ...

87.62 u = (84 u × Percent Abundance of Sr-84) + (86 u × Percent Abundance of Sr-86) + (87 u × Percent Abundance of Sr-87) + (88 u × Percent Abundance of Sr-88)

To find which isotope has the highest percent abundance, we need to look for the isotope with the smallest mass because it would contribute the most to the average atomic mass.

Among the given isotopes, Sr-84 has the smallest mass (84 u), so it should have the highest percent abundance to bring down the average atomic mass to 87.62 u.

Therefore, strontium-84 (Sr-84) is predicted to have the highest percent abundance.

Answer 2

The isotope with the highest percent abundance of strontium is strontium-87.

Step-by-step explanation:

In order to predict which isotope of strontium has the highest percent abundance, we need to consider the ratio of 87Sr to 86Sr. According to the given information, the ratio of the initial number of 87Sr to 86Sr atoms is 0.71.

This means that the isotope with the highest percent abundance will have a higher number of 87Sr atoms compared to 86Sr atoms. Therefore, the isotope with the highest percent abundance would be strontium-87.

To defend this answer, we can compare the known average atomic mass of strontium (87.62 u) to the atomic masses of the other isotopes. The isotope with the highest percent abundance would contribute the most to the average atomic mass, therefore indicating its higher abundance.