Average Atomic Mass and Isotopes

The video tutorial covers the concept of average atomic mass, explaining how it is calculated using the percent abundance and atomic mass of isotopes. The instructor provides detailed examples for elements like boron, argon, carbon, and magnesium, demonstrating the step-by-step process of converting percentages to decimals and calculating the average atomic mass. The tutorial emphasizes the importance of accuracy in calculations and how the results should align closely with the atomic masses listed on the periodic table.

What is the key factor in determining the average atomic mass of an element?

• The chemical reactivity of the element

• The number of electrons in the outer shell

• The percent abundance and atomic mass of its isotopes

• The number of protons in the nucleus

How do you convert a percentage to a decimal for calculations?

• Multiply by 10

• Divide by 1000

• Move the decimal point two places to the left

• Add 0.5 to the percentage

What is the average atomic mass of boron if boron-11 is 80.2% abundant and boron-10 is 19.8% abundant?

• 9.50

• 10.75

• 12.00

• 11.00

Which isotope of argon has the highest percent abundance?

• Argon-40

• All isotopes have equal abundance

• Argon-38

• Argon-36

What is the average atomic mass of argon given its isotopes and abundances?

• 39.95

• 38.00

• 36.00

• 40.00

What is the percent abundance of carbon-12?

• 100.00%

• 98.89%

• 50.00%

• 1.10%

Calculate the average atomic mass of carbon using its isotopes.

• 12.00

• 13.00

• 12.01

• 11.00

Which magnesium isotope is the most abundant?

• Magnesium-26

• Magnesium-25

• All isotopes have equal abundance

• Magnesium-24

What is the average atomic mass of magnesium given its isotopes and abundances?

• 26.00

• 23.98

• 24.30

• 25.00

Why is it important to check the calculated average atomic mass against the periodic table?

• To ensure the element is stable

• To determine the element's reactivity

• To find the number of isotopes

• To verify the calculation is correct