what are the charges on group 1 elements?
1+
what are the charges on group 2 elements?
+2
what are the charges on group 3 elements?
+3
what are the charges on group 5 elements?
-3
what are the charges on group 6 elements?
-2
what are the charges on group 7 elements?
-1
what is the conservation of mass
cannot create or destroy atoms, only move them around