When a chemical reaction occurs, matter isthe amount of each atom is the reactants will be different form the amount in the. Are used to show how many of each molecule in present, andare used to show how many of eachis present.

plz explain more

Explanatin:

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.