Calculating Average Atomic Masses of Isotopes in Chemistry

The video tutorial explains the concept of isotopes and how to calculate the average atomic mass using Gallium, Rubidium, and Magnesium as examples. It covers the meaning of 'respectively' in the context of isotopes, demonstrates the calculation process for Gallium and Magnesium, and discusses the abundance of Rubidium isotopes based on atomic weight.

What does the term 'respectively' imply in the context of isotopes?

• The masses are listed in alphabetical order.

• The isotopes are listed in order of atomic number.

• The first mass corresponds to the first isotope mentioned, and the second mass to the second isotope.

• The isotopes are listed in order of abundance.

How do you express the percentage abundance of an isotope as a decimal?

• Multiply by 100

• Move the decimal two places to the left

• Add 0.1 to the percentage

• Divide by 1000

What is the average atomic mass of Gallium as calculated in the video?

• 68.92 amu

• 70.92 amu

• 71.72 amu

• 69.72 amu

Why is the average atomic mass of Gallium closer to 69 than 71?

• Both isotopes are equally abundant.

• Gallium 71 has a higher atomic mass.

• Gallium 69 is more abundant.

• Gallium 71 is more abundant.

What is the significance of the weighted average in determining atomic mass?

• It reflects the relative abundance of each isotope.

• It indicates the isotope with the highest atomic number.

• It shows the most common isotope.

• It is used to calculate the density of the element.

Which isotope of Gallium is more abundant?

• Gallium 69

• Gallium 71

• Both are equally abundant

• Neither is abundant

What does the atomic mass of Rubidium on the periodic table suggest about its isotopes?

• The atomic mass is an average of all elements.

• Rubidium 87 is more abundant.

• Rubidium 85 is more abundant.

• Both isotopes are equally abundant.

How can you determine which isotope of Rubidium is more abundant without calculations?

• By looking at the atomic mass on the periodic table

• By comparing the atomic masses

• By checking the atomic number

• By measuring the isotopes' densities

What is the first step in calculating the average atomic mass of Magnesium?

• Subtract the smallest mass from the largest

• Add the masses of all isotopes

• Multiply each isotope's mass by its abundance as a decimal

• Divide the total mass by the number of isotopes

How many stable isotopes does Magnesium have?

• Four

• Three

• Two

• One