Before a blast, metals bristle as electrons flee
Lights, camera, kaboom! With snapshots from a high-speed camera, chemists can finally explain why sodium and other alkali metals blow up in water.
Just before the explosion, spikes burst from the metal’s smooth surface, setting off a chain reaction that ignites the metal. The blast’s film debut, appearing online January 26 in Nature Chemistry, offers a long-awaited explanation of a classic chemical reaction demonstrated in classrooms worldwide.
“What we found out is that there's a crucial piece of the puzzle that precedes the explosion,” says computational chemist Pavel Jungwirth of the Academy of Sciences of the Czech Republic in Prague.
In textbooks, chemists describe the reaction in simple terms. Alkali metals, a group of elements including potassium and sodium, are highly reactive. In a splash of water, the metal