Light-Induced Chemical Chain Reaction

One single particle of light can trigger a massive chemical chain reaction. In the dark,

methane and chlorine gas just sit there, doing nothing. But hit them with a flash of blue

light, and a chlorine molecule splits into two super-reactive radicals. A radical is an

atom with an unpaired electron, and it's desperate to react. It viciously rips

a hydrogen from a methane molecule, creating a new radical. This new radical then attacks another

chlorine molecule, continuing the cycle. This chain reaction can create thousands of product molecules

from just one initial spark, only stopping when two radicals finally meet and pair up.