Please tell me why and how do chemist use the periodic table? Please describe how it describes the following? Groups, Periods, valence electrons, highly reactive, non reactive, size and
mass of atom.

(I need answer ASAP please)

Ammonium perchlorate nh4clo4 is the solid rocket fuel used by the u.s. space shuttle. it reacts with itself to produce nitrogen gas n2 , chlorine gas cl2 , oxygen gas o2 , water h2o , and a great deal of energy. what mass of nitrogen gas is produced by the reaction of 2.1g of ammonium perchlorate?