Grade 9 Relative Mass Worksheet

Grade 9 Relative Mass Worksheet

Read each question carefully and answer to the best of your ability. Show all your work for calculation questions.

1. What is the standard unit used to express relative atomic mass?

2. An element has two isotopes. Isotope A has an abundance of 75% and a mass of 10.0 amu. Isotope B has an abundance of 25% and a mass of 12.0 amu. What is the average atomic mass of the element?

3. The relative atomic mass is a weighted average of the masses of an element's  .

4. The mass of a proton is approximately   amu.

5. Carbon-12 is used as the reference standard for defining the  .

6. Explain why the average atomic mass of an element is rarely a whole number.

7. Observe the diagram below showing a simplified atomic structure. Label the subatomic particles and indicate which particles contribute significantly to the atomic mass.

8. All atoms of a given element have the same atomic mass.

9. The mass of electrons is negligible when calculating the relative atomic mass.

10. Chlorine has two main isotopes: Cl-35 (mass = 34.969 amu) and Cl-37 (mass = 36.966 amu). If the natural abundance of Cl-35 is 75.77% and Cl-37 is 24.23%, calculate the average atomic mass of chlorine.