Polyatomic Ions O N O O O O O P S O O O O O N H H polyatomic ion: You know how single atoms can ionically bond with other atoms as… ions? Well, a group of atoms can act as a cation or an anion (almost always) , as well. Individually, these groups of atoms are known as a: polyatomic ion: a tightly (covalently) bonded group of atoms with a + or– charge (almost always) , overall N H N O O H H O O O P S O O O O O

Common Polyatomic Ions (yes, write all of this down) Name Formula Charge ammonium NH4+ 1+ hydroxide OH– 1– acetate C2H3O2– permanganate MnO4– nitrate NO3– chlorate ClO3– hydrogencarbonate (bicarbonate is what everyone actually calls it, you need to know this) HCO3– carbonate CO32– 2– sulfate SO42– phosphate PO43– 3– handout list of polyatomics

many end in –ate Monatomic Polyatomic nitride nitrate N3– NO3– the anions all end in –ide many end in –ate Note: remember, though, all monatomic cations have the same name as the atom Monatomic Polyatomic nitride nitrate N3– NO3– ammonium NH4+ chloride chlorate Cl– ClO3– hydroxide OH– Interestingly, most polyatomic ions, that we care about, have oxygens in their formulas (probably has something to do with the part of the atmosphere we care about) sulfide sulfate S2– SO42– phosphide phosphate P3– PO43–

Names and Formulas for Compounds with Polyatomic Ions Same rules as with all compounds. Example: calcium nitrate symbols of ions charges (as superscripts) crisscross (to get subscripts) erase charges use ( ) for multiple polyatomic ions Ca NO3 Ca2+ NO3– Ca2+ NO3– Ca NO3 2 ? Ca(NO3)2

(use your polyatomic ions sheet) Write the formulas for the following compounds with polyatomic ions. (use your polyatomic ions sheet) ammonium nitrate calcium phosphate iron(III) carbonate NH4+ NO3– NH4NO3 Ca2+ PO43– Ca3(PO4)2 Fe3+ CO32– Fe2(CO3)3

1. Which of the following are positively charged polyatomic ions? Quick Quiz! 1. Which of the following are positively charged polyatomic ions? 1) ammonium ion 2) nitrate ion 3) iron(III) ion 1 only 2 only 1 and 2 1 and 3 NH4+ NO3– Fe3+

2. What is the correct name for Mg(OH)2 ? magnesium oxide Quick Quiz. 2. What is the correct name for Mg(OH)2 ? magnesium oxide magnesium hydroxide magnesium(II) hydroxide magnesium(II) hydroxate

Cu+ SO42– 3. What is the correct formula for copper(I) sulfate? CuS Quick Quiz. 3. What is the correct formula for copper(I) sulfate? CuS CuSO4 Cu2SO4 Cu(SO4)2 Cu+ SO42–

4. Which one of the following formulas is named correctly? Quick Quiz. 4. Which one of the following formulas is named correctly? sodium bicarbonate, Na2CO3 potassium nitrate, KNO2 sodium acetate, NaC2H3O2 lithium sulfide, Li2SO4