You are watching: Polyatomic ions are a group of
Some ion consist of teams of atoms bonded together and also have an overall electric charge. Because these ion contain an ext than one atom, castle are called polyatomic ions. Polyatomic ions have actually characteristic formulas, names, and also charges that need to be memorized. For example, NO3− is the nitrate ion; it has one nitrogen atom and also three oxygen atoms and also an overall 1− charge. Table (PageIndex1) list the most common polyatomic ions.
|acetate ion||C2H3O2− (also written CH3CO2−)|
|hydrogen lead carbonate ion (bicarbonate ion)||HCO3−|
|hydrogen phosphate ion||HPO42−|
|dihydrogen phosphate ion||H2PO4−|
|hydrogen sulfate ion (bisulfate ion)||HSO4−|
The dominance for building formulas for ionic compound containing polyatomic ion is the exact same as for formulas containing monatomic (single-atom) ions: the confident and an adverse charges have to balance. If an ext than one of a specific polyatomic ion is needed to balance the charge, the entire formula for the polyatomic ion need to be enclosed in parentheses, and the numerical subscript is inserted outside the parentheses. This is to display that the subscript uses to the entire polyatomic ion. An example is Ba(NO3)2.
Writing Formulas for Ionic compound Containing Polyatomic Ions
Writing a formula for ionic link containing polyatomic ions also involves the same steps as because that a binary ionic compound. Write the symbol and charge the the cation complied with by the symbol and also charge of the anion.
Example (PageIndex1): Calcium Nitrate
Write the formula for calcium nitrate.
|1. Create the symbol and also charge that the cation (metal) very first and the anion (nonmetal) second.||(ceCa^2+ : : : : : ceNO_3^-)|
|2. Transpose only the variety of the optimistic charge to become the subscript the the anion and also the number only of the an adverse charge to come to be the subscript the the cation.|
Example (PageIndex3): specify name Ionic Compounds
Write the proper name because that each ionic compound.(NH4)2S AlPO4, Fe3(PO4)2