Pl why do atoms bond? a. they want to fill up their outer electron shell in order to become stable. b. they have too many electrons on their inner shell and need to give some away. c. some atoms are sticky so they stick to other atoms. d. they want to fill up their nucleus in order to become stable. which of the following best describes all types of chemical reactions? a. the decomposition of particles b. forming or breaking bonds c. the combustion of a substance d. mixing two substances