Final answer:
To differentiate between a binary ionic compound and one with a polyatomic ion, examine the chemical formula for the presence of a metal and nonmetal or a charged group of atoms,
Step-by-step explanation:
To tell the difference between a binary ionic compound and one containing a polyatomic ion, you should look at the formula of the compound. A binary ionic compound will consist of one metal and one nonmetal, represented by their chemical symbols.
For example, NaCl is composed of sodium (Na+) and chloride (Cl−) ions. On the other hand, a compound containing a polyatomic ion will include a group of atoms behaving as a unit with a charge. For instance, in Ba(NO3)2, 'NO3' is recognized as the nitrate ion (NO3−), a polyatomic ion.
This compound includes the barium ion (Ba²+) which balances the charges of the two nitrate ions. Another indicator is the use of parentheses which is common when indicating that a group of atoms forms a unit, such as in calcium phosphate, Ca3(PO4)2.