What substances are commonly formed during a chemical reaction but we can't see them?

How do you identify the anode on a power source such as a battery? how do you identify the cathode? how are terms anion and cation?

Voltaic cells produce a positive overall charge. what does this indicate? a. the reaction is likely to be endothermic. b. the reaction is spontaneous. c. the reaction is not likely to occur. d. the reaction is not spontaneous.

Which reason best explains why metals are malleable? a)because they have delocalized electrons b)because they have localized electrons c)because they have ionic bonds d)because they have rigid bonds