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The Empty Seat: How Mendeleev Described an Element Before It Existed (Chemistry Level 8)
Season 1
Episode 3
Published 3 days, 18 hours ago
Description
So how do you describe something before it exists? We'll follow Mendeleev's trick first, then crack open an atom and find that the clue he was sorting by wasn't what really makes an element itself.
Gallium's real address isn't 'weighs about 68'. It's 'has 31 protons'. The listener can now say what atomic number is (number of protons) and what mass number is (protons + neutrons, a plain count with no units). They can also say why the table is really built on the first one.
Sources:
- https://en.wikipedia.org/wiki/Gallium
- https://www.reagent.co.uk/blog/paul-emile-lecoq-de-boisbaudran/
- https://periodic-table.rsc.org/element/31/gallium
Source: Chemistry Level 8, Chapter 2: Atoms and the Periodic Table (1/4)
Sections: 2.1, 2.2
Style: Exam prep
Length: 1041 words, 6 min target
Generated: 2026-10-24