... 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. A "dimer" forms when two of the same molecules combine (dimerize). Draw a Lewis structure for each of the substances below and indicate which are free radicals. For a free radical the unpaired electron goes on the least electronegative element, which is usually the central atom. Key: ... y = Yes ... n = No 1. BrO2 2. OCl2 3. ClO2 4. NO2- Submit AnswerRetry Entire Group