Binary ionic compounds (compounds consisting of two different ions)
binary ionic compounds are formed between a metal and a nonmetal. metallic elements tend to lose electrons (forming positive ions) in order to become isoelectronic with (to have the same number of electrons as) a noble gas.
The conversion of reactants into products in a chemical reaction is often accompanied by some features which can be easily observed easily. the important characteristics of chemical reactions are: evolution of a gas formation of a precipitate, change in colour, change in temperature and change in state.