Polyatomic Nomenclature

 In polyatomic compounds, a positive ion and negative ion attract one another to form an ionic bond.  To write formulas for polyatomic compound, determine what charge is on the positive ion and what charge is on the negative ion. Then, write the formula so that the compound is neutral…  the ‘criss-cross’ method may be useful

Common Polyatomic Ions to LEARN 1+ NH 4 + ammonium 1- ClO 4 - perchlorate ClO 3 - chlorate ClO 2 - chlorite ClO - hypochlorite NO 3 - nitrate NO 2 - nitrite CH 3 COO - acetate (-or- C 2 H 3 O 2 - ) CN - cyanide SCN - thiocyanate OH - hydroxide MnO 4 - permanganate HCO 3 - bicarbonate (-or- hydrogen carbonate) HSO 4 - bisulfate (-or- hydrogen sulfate) H 2 PO 4 - dihydrogen phosphate 2- CO 3 2- carbonate SO 4 2- sulfate SO 3 2- sulfite S 2 O 3 2- thiosulfate CrO 4 2- chromate Cr 2 O 7 2- dichromate HPO 4 2- biphosphate (-or- hydrogen phosphate) 3- BO 3 3- borate PO 4 3- phosphate PO 3 3- phosphite

Polyatomic Ions ClO - ClO 2 - ClO 3 - ClO 4 - hypochlorite chlorite chlorate perchlorate SO 2 2- SO 3 2- SO 4 2- SO 5 2- hyposulfite sulfite sulfate persulfate

Polyatomic Nomenclature  For example… magnesium nitrate  forms from:  the magnesium ion, Mg 2+  and the nitrate ion, NO 3 -  So, the formula is Mg(NO 3 ) 2

Polyatomic Nomenclature 1.calcium sulfate Ca 2+ SO 4 2- CaSO 4 2.ammonium oxide NH 4 + O 2- (NH 4 ) 2 O

Polyatomic Nomenclature 3.chromium(III) nitrate Cr 3+ NO 3 - Cr(NO 3 ) 3 4.titanium phosphate Ti 2+ PO 4 3- Ti 3 (PO 4 ) 2

Ionic Nomenclature  Ionic bonding occurs between…  a metal & a non-metal  To name an ionic compound:  name the metal (name the cation)  name the non-metal, adding an –ide ending (name the anion)

Polyatomic Nomenclature  Polyatomic compounds have 3 or more elements and involve both ionic and covalent bonding.  To name polyatomic compounds:  name the cation  name the positive ion – a metal or ammonium (NH 4 + )  name the anion  name the negative ion – a non-metal-ide or, a polyatomic ion

Common Polyatomic Ions to LEARN 1+ NH 4 + ammonium 1- ClO 4 - perchlorate ClO 3 - chlorate ClO 2 - chlorite ClO - hypochlorite NO 3 - nitrate NO 2 - nitrite CH 3 COO - acetate (-or- C 2 H 3 O 2 - ) CN - cyanide SCN - thiocyanate OH - hydroxide MnO 4 - permanganate HCO 3 - bicarbonate (-or- hydrogen carbonate) HSO 4 - bisulfate (-or- hydrogen sulfate) H 2 PO 4 - dihydrogen phosphate 2- CO 3 2- carbonate SO 4 2- sulfate SO 3 2- sulfite S 2 O 3 2- thiosulfate CrO 4 2- chromate Cr 2 O 7 2- dichromate HPO 4 2- biphosphate (-or- hydrogen phosphate) 3- BO 3 3- borate PO 4 3- phosphate PO 3 3- phosphite

Polyatomic Nomenclature 1.NH 4 + and PO 4 3- (NH 4 ) 3 PO 4 ammonium phosphate 2.H + and BO 3 3- H 3 BO 3 hydrogen borate 3.Li + and CO 2 2- Li 2 CO 2 lithium carbonite

Polyatomic Nomenclature