Year 10 - Science
Relative formula mass
Atomic structure and the periodic table
Study Hub
Study Guides
This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers the atomic model, relative atomic mass, isotopes, and the structure of the modern periodic table. It explains how atomic structure influences element positioning, properties, and reactivity. The focus is on identifying trends and using models to develop scientific explanations.
Lesson Summary
You will learn to calculate the relative formula mass of substances using data taken from a periodic table.
Key Notes
- The relative atomic mass is the mean mass of an atom compared to 1/12 of the mass of a carbon-12 atom.
- The relative formula mass (RFM or Mr) is the sum of the relative atomic masses of all the atoms in a chemical formula.
- %mass of an element in a compound = (relative mass of element in compound ÷ RFM of compound) × 100
Vocabulary To Learn
- relative atomic mass: RAM is the mean mass of an atom relative to 1/12th the mass of an atom of carbon–12.
- relative formula mass: (RFM or Mr) is the sum of the relative atomic masses of all the atoms in a chemical formula.
Common Mistakes To Avoid
- Pupils may use the atomic number rather than mass when calculating the relative formula mass. Also, the number of atoms can be missed for the percentage of an element in a compound.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
The relative atomic mass is the mean mass of an atom compared to 1/12 of the mass of a carbon-12 atom. The relative formula mass (RFM or Mr) is the sum of the relative atomic masses of all the atoms in a chemical formula.
2. Define this scientific word and use it in context. 'relative atomic mass'
RAM is the mean mass of an atom relative to 1/12th the mass of an atom of carbon–12. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils may use the atomic number rather than mass when calculating the relative formula mass. Also, the number of atoms can be missed for the percentage of an element in a compound. Correction: Emphasise that atomic mass is the larger number for each element on the periodic table and encourage pupils to use the key present to help them identify the mass.
More Lessons In This Unit
- Atomic number and mass number Study Guide
- Atomic structure (negligible electron mass) Study Guide
- Atomic structure (very small electron mass) Study Guide
- Atoms, elements and compounds Study Guide
- Developing a model for atoms Study Guide
- Development of the periodic table Study Guide
- Isotopes Study Guide
- Isotopes and relative atomic mass Study Guide
- Modern periodic table and electron configuration Study Guide
- Using the periodic table: atomic and mass number Study Guide
Browse all guides in the Year 10 Science guide library.