A complete revision and exam practice pack for SC4a Elements and the Periodic Table, covering the full Pearson Edexcel GCSE Chemistry (9–1) Separate Science specification for this topic (C1.13–C1.14).

Topic Mastery Sheet (PDF) - a comprehensive student reference that tells the story of Mendeleev’s periodic table as a genuine piece of scientific reasoning rather than a list of facts. The sheet sets out the problem Mendeleev faced (around 60 known elements with no satisfying organisational system), then traces his five key moves: ordering by relative atomic mass; grouping by chemical properties; swapping pairs where mass order conflicted with chemical behaviour; leaving deliberate gaps for undiscovered elements; and predicting the properties of those missing elements from the trends in neighbouring groups. The prediction of gallium (‘eka-aluminium’) is given as a detailed case study - Mendeleev’s 1871 predictions are listed alongside gallium’s actual properties when it was discovered in 1875, showing the extraordinary accuracy of his method. The section on why scientists were initially sceptical addresses each objection honestly, then explains how the discovery of gallium (1875), scandium (1879) and germanium (1886) converted almost all remaining doubters. The absence of noble gases from Mendeleev’s 1869 table is explained: they had not been discovered - they slotted in as a new group when found in 1894–98, without disrupting anything. The stretch section covers Newlands, Lothar Meyer, and the 118-element modern table.

Student Exam Practice Sheet (PDF + DOCX) - seven exam-style questions covering the ordering property used, describing the ordering method, why pairs were swapped, why gaps were left, how properties were predicted, how ideas were supported by evidence, and why group 0 is absent from 1869.

Teacher Answer Key (PDF + DOCX) - full tick-point mark scheme with examiner notes.

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