When sodium meets mercury, the result is no ordinary metal—it’s sodium amalgam, a silvery alloy once used in industry. But behind its shine lies a chemical that reacts violently with water and spreads ...

Correction: at 12:50 I said that pure nitrogen is denser than air, but that isn't true. The specific gravity of nitrogen vs dry air at STP is ~0.97, meaning that it should rise slightly, but the ...