Free Radicals are molecules or ions that have an unpaired electron. They tend to be very reactive and are thought to contribute to the aging process. dimer forms when two of the same molecules combine (dimerize). Draw Lewis structure for each of the substances below and indicate which are free radicals. For free radical the unpaired electron goes on the least electronegative element; which is usually the central atom_ Key: Yes n - No 0z CIOz NO BrO3