Grade 8 Science: Relative Mass

Grade 8 Science: Relative Mass

Read each question carefully and answer to the best of your ability. Show all your work where applicable.

Understanding Relative Atomic Mass

The mass of atoms is very small and difficult to work with directly. Scientists use a concept called 'relative atomic mass' to compare the masses of different atoms. This is based on a standard, typically carbon-12. The relative atomic mass of an element is the weighted average of the masses of its isotopes.

1. The mass of an atom is primarily determined by the number of   and   in its nucleus.

2. Electrons have a   mass compared to protons and neutrons.

3. The standard used to define relative atomic mass is an atom of  -12.

1. Which subatomic particle has a relative mass of approximately 1 atomic mass unit (amu)?

2. If an element has two common isotopes, one with a mass of 10 amu (20% abundance) and another with a mass of 11 amu (80% abundance), what is its approximate relative atomic mass?

1. Explain why electrons are generally not included when calculating the mass number of an atom.

2. Define 'isotope' and explain how isotopes of the same element differ in terms of relative mass.

1. The atomic number of an element determines its relative atomic mass.

2. Relative atomic mass is always a whole number.

Refer to the diagram of atomic structure below to answer the following question.

3. In the provided diagram of an atom, identify the subatomic particles that contribute most significantly to the atom's relative mass.