Mendeleev's Genius (1869)
Part of Development of Periodic Table · GCSE GCSE Chemistry revision
This key facts covers Mendeleev's Genius (1869) within Development of Periodic Table for GCSE Chemistry. Revise Development of Periodic Table in Atomic Structure for GCSE Chemistry with 20 exam-style questions and 21 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 5 of 13
Practice
20 questions
Recall
21 flashcards
💡 Mendeleev's Genius (1869)
What made Mendeleev different? He was willing to break the rules when the evidence demanded it.
His key innovations:
- Left GAPS for undiscovered elements
- Predicted properties of missing elements with remarkable accuracy
- Swapped the order of some elements when their properties didn't fit (e.g., tellurium and iodine)
His predictions came true:
Mendeleev predicted "eka-aluminium": atomic weight ≈ 68, density ≈ 5.9 g/cm³, low melting point
Gallium discovered (1875): atomic weight = 69.7 ✓, density = 5.91 g/cm³ ✓, melts at 30°C ✓
Germanium (1886) matched his "eka-silicon" prediction
Scandium (1879) matched his "eka-boron" prediction
This proved his table revealed real patterns in nature!
Keep building this topic
Read this section alongside the surrounding pages in Development of Periodic Table. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Development of Periodic Table
John Newlands proposed the Law of Octaves in 1866. What did he notice about the elements?
Give two reasons why Newlands' Law of Octaves was not accepted by the scientific community at the time.
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