How to Calculate the Average Atomic Mass - 3 EASY STEPS

The video tutorial explains the concept of atomic mass, differentiating between mass number and average atomic mass. It introduces isotopes and their role in determining atomic mass, emphasizing the importance of percent abundance. The tutorial provides a step-by-step guide to calculating average atomic mass using examples of potassium and gallium isotopes. It highlights the significance of rounding in periodic tables and introduces atomic mass units (AMU).

What is the difference between mass number and average atomic mass?

• Mass number is a decimal, average atomic mass is a whole number.

• Mass number is the sum of protons and neutrons, average atomic mass is a weighted average of isotopes.

• Mass number is the number of electrons, average atomic mass is the number of protons.

• Mass number and average atomic mass are the same.

Which of the following statements about isotopes is true?

• Isotopes of an element have the same mass.

• Isotopes of an element have different symbols.

• Isotopes of an element have different numbers of protons.

• Isotopes of an element have different masses but the same number of protons.

What does percent abundance indicate?

• The percentage of electrons in an isotope.

• The percentage of protons in an isotope.

• The percentage of an element's isotopes in a sample.

• The percentage of neutrons in an isotope.

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

• Convert percent abundances to decimals.

• Add the masses of all isotopes.

• Divide the mass of each isotope by 100.

• Multiply the mass of each isotope by its percent abundance.

How do you find the average atomic mass after converting percent abundances to decimals?

• Multiply the mass of each isotope by its decimal and add the results.

• Subtract the smallest decimal from the largest.

• Divide the total mass by the number of isotopes.

• Add the decimals together.

Why might the calculated average atomic mass differ slightly from the periodic table?

• Due to changes in atomic structure.

• Because of rounding differences.

• Due to different isotopes being used.

• Because of incorrect calculations.

In the example of gallium, what are the two naturally occurring isotopes?

• Gallium 69 and Gallium 71

• Gallium 67 and Gallium 69

• Gallium 68 and Gallium 70

• Gallium 70 and Gallium 72