What’s really going on when the sodium ’explodes’ in water?

Dropping a chunk of pure sodium into water is a classic classroom science experiment. But what’s really going on when the sodium ’explodes’ in water? Scientists have finally captured the action using high-speed video cameras and discovered that less than a millisecond after sodium and water meet, the sodium contorts into a sea-urchin-like shape, growing spikes that shoot out into the water and initiate a runaway reaction Find out more: Credit: Mason et al.