Year 10 - Science
Development of the periodic table
Atomic structure and the periodic table
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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 describe the development of the periodic table and explain its current form.
Key Notes
- Dalton (1803) arranged known elements in order of atomic weights.
- Newlands (1865) noticed that every eighth element, in order of atomic mass, repeated similar properties.
- Mendeleev swapped the order of atomic weights in order to fit elements better into groups of similar properties.
- Mendeleev's periodic table had gaps and he predicted missing elements that were later found.
- Mendeleev was not aware of isotopes, so was unable to explain why the ordering by atomic weight was not always correct.
Vocabulary To Learn
- isotope: An atom of an element with the same number of protons, but different mass numbers due to different numbers of neutrons.
- atomic weight: The historical name for atomic mass, i.e. the ratio of the mass of an atom compared to a standard.
- relative atomic mass: The mean mass of an atom compared to 1/12 of the mass of a carbon–12 atom.
- Dmitri Mendeleev: A scientist who devised the periodic table of elements.
Common Mistakes To Avoid
- Pupils often believe that the when the periodic table was devised, scientists knew about the subatomic particles.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Dalton (1803) arranged known elements in order of atomic weights. Newlands (1865) noticed that every eighth element, in order of atomic mass, repeated similar properties.
2. Define this scientific word and use it in context. 'isotope'
An atom of an element with the same number of protons, but different mass numbers due to different numbers of neutrons. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils often believe that the when the periodic table was devised, scientists knew about the subatomic particles. Correction: Emphasise when the subatomic particles were discovered in comparison to when Mendeleev devised his periodic table.
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
- Isotopes Study Guide
- Isotopes and relative atomic mass Study Guide
- Modern periodic table and electron configuration Study Guide
- Relative formula mass Study Guide
- Using the periodic table: atomic and mass number Study Guide
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