Polyatomic Ionic Compounds Formula to Name

Definition Polyatomic Ion- more than one atom that together have a charge Polyatomic Ionic Compound- compound containing at least one polyatomic ion + Cation - Polyatomic Anion Polyatomic Ionic Compound 2

Common Polyatomic Ions The Appendix of your book (Page A-2) has the following chart COMMON POLYATOMIC IONS Acetate, CH3COO-1 or C2H3O2-1 Ammonium NH4+1 Bromate, BrO3-1 Bromite, BrO2-1 Carbonate, CO3-2 Carbonite, CO2-2 Chlorate, ClO3-1 Chlorite, ClO2-1 Chromate, CrO4-2 Cyanide, CN-1 Dichromate, Cr2O7-2 Dihydrogen phosphate, H2PO4-1 Hydrogen carbonate or bicarbonate, HCO3-1 Hydrogen phosphate or biphosphate, HPO4-2 Hydrogen sulfate or bisulfate, HSO4-1 Hydroxide, OH-1 Hypochlorite, ClO-1 Iodate, IO3-1 Iodite, IO2-1 Nitrate, NO3-1 Nitrite, NO2-1 Oxalate, C2O4-2 Perchlorate, ClO4-1 Permanganate, MnO4-1 Peroxide, O2-2 Phosphate, PO4-3 Phosphite, PO3-3 Silicate, SiO3-1 Sulfate, SO4-2 Sulfite, SO3-2

Help Identifying Polyatomic Ions The only cation (front-half) polyatomic ion is “NH4” All other polyatomic ions are anions (back-half) The subscripts within the polyatomic ion is important (it must match exactly with the one on your ion list) If there are parenthesis, the polyatomic ion is inside (ignore the number outside) 4

Practice Identifying Polyatomic Ions NaNO3 NH4Cl Ca(OH)2 (NH4)3PO4 K2CO3 Example: Identify and name the polyatomic ion in each compound

Practice Identifying Polyatomic Ions NaNO3 NH4Cl Ca(OH)2 (NH4)3PO4 K2CO3 Nitrate Ammonium Hydroxide Ammonium & phosphate Carbonate Example: Identify and name the polyatomic ion in each compound

Identifying & Naming Polyatomic Ionic These compounds have: More than 2 capital letters (non starting with H) Contain at least 1 metal & 1 non-metal To name these compounds: Write the name of the cation (the metal element name or “Ammonium” for “NH4”) If the anion is a polyatomic ion, write the polyatomic ion’s name just as it is If the anion is a single non-metal element, write its name with the suffix “-ide” 7

Example #4 NaNO3

NaNO3 Example #4 Sodium Nitrate Cation Polyatomic Anion “Sodium” 9

Example #5 K2SO4

K2SO4 Example #5 Potassium sulfate Cation Polyatomic Anion “Potassium” 11

Example #6 Ca(OH)2

Ca(OH)2 Example #6 Calcium hydroxide Cation Polyatomic Anion “Calcium” 13

Example #7 (NH4)2S

(NH4)2S Example #7 Ammonium sulfide Polyatomic Cation Anion “Ammonium” “sulfur” becomes “sulfide” Ammonium sulfide 15

Write the name for the following compounds Let’s Practice Ca(NO3)2 Na3PO4 NH4ClO K2CO3 Example: Write the name for the following compounds

Write the name for the following compounds Let’s Practice Ca(NO3)2 Na3PO4 NH4ClO K2CO3 Calcium nitrate Sodium phosphate Ammonium hypochlorite Potassium carbonate Example: Write the name for the following compounds

Polyatomic Ionic Compounds Name to Formula

Definition Polyatomic Ion- more than one atom that together have a charge Polyatomic Ionic Compound- compound containing at least one polyatomic ion + Cation - Polyatomic Anion Polyatomic Ionic Compound

Identifying & Naming Polyatomic Ionic These compounds: Do not end with “-ide” (except hydroxide & cyanide) Do not use covalent prefixes To write these formulas: Write the symbol & charge of the cation & anion Add additional cations or anions to have a neutral compound Use subscripts to show the number of ions When using subscripts with a polyatomic ion, you must put the polyatomic ion in parenthesis.

Example #3 Sodium carbonate

Example #3 Na+1 Cation Sodium carbonate Polyatomic Anion CO3-2

Na2CO3 Example #3 Sodium carbonate Cation Polyatomic Anion Na+1 +1 + -2 = -1 Polyatomic Anion Na+Na+CO32- +1 + 1 + -2 = 0 CO3-2 Na2CO3 The subscript “2” is used to show that 2 cations are needed.

Example #4 Magnesium nitrate

Example #4 Mg+2 Cation Magnesium nitrate Polyatomic Anion NO3-1

Mg(NO3)2 Example #4 Magnesium nitrate Cation Polyatomic Anion Mg+2 +2 + -1 = 1 Magnesium nitrate Mg+2NO3- NO3- Polyatomic Anion +2 + -1 + -1 = 0 NO3-1 The subscript “2” is used to show that 2 anions are needed. Mg(NO3)2 Use parenthesis when adding subscripts to polyatomic ions

Write the following chemical formulas Let’s Practice Sodium nitrate Calcium chlorate Potassium sulfite Calcium hydroxide Example: Write the following chemical formulas

Write the following chemical formulas Let’s Practice Sodium nitrate Calcium chlorate Potassium sulfite Calcium hydroxide NaNO3 Ca(ClO3)2 K2SO3 Ca(OH)2 Example: Write the following chemical formulas