Ionic Compound Formulas

IonsIons  Cation: A positive ion  Mg 2+  Anion: A negative ion  Cl   Cation: A positive ion  Mg 2+  Anion: A negative ion  Cl 

Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+H+H+H+ Li + Na + K+K+K+K+

Predicting Ionic Charges Group 2: Loses 2 electrons to form 2+ ions Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+

Predicting Ionic Charges Group 13: Loses 3 Loses 3 electrons to form 3+ ions B 3+ Al 3+ Ga 3+

Predicting Ionic Charges Group 14: Lose 4 Lose 4 electrons or gain 4 electrons? Neither! Group 13 elements rarely form ions.

Predicting Ionic Charges Group 15: Gains 3 Gains 3 electrons to form 3- ions N 3- P 3- As 3- Nitride Phosphide Arsenide

Predicting Ionic Charges Group 16: Gains 2 Gains 2 electrons to form 2- ions O 2- S 2- Se 2- Oxide Sulfide Selenide

Predicting Ionic Charges Group 17: Gains 1 Gains 1 electron to form 1- ions F 1- Cl 1- Br 1- Fluoride Chloride Bromide I 1- Iodide

Predicting Ionic Charges Group 18: Stable Noble gases do not form ions! Stable Noble gases do not form ions!

Predicting Ionic Charges Groups : Many transition elements Many transition elements have more than one possible oxidation state. have more than one possible oxidation state. Iron(II) = Fe 2+ Iron(III) = Fe 3+

Predicting Ionic Charges Groups : Some transition elements Some transition elements have only one possible oxidation state. have only one possible oxidation state. Zinc = Zn 2+ Silver = Ag +

Writing Ionic Compound Formulas Example: Iron(III) chloride 1. Write the formulas for the cation and anion, including CHARGES! Fe 3+ Cl - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 3

Writing Ionic Compound Formulas Example: Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! Al 3+ S Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 23

Naming Ionic Compounds  Cation first, then anion  Monatomic cation = name of the element  Ca 2+ = calcium ion  Monatomic anion = root + -ide  Cl  = chloride  CaCl 2 = calcium chloride  Cation first, then anion  Monatomic cation = name of the element  Ca 2+ = calcium ion  Monatomic anion = root + -ide  Cl  = chloride  CaCl 2 = calcium chloride

Naming Ionic Compounds (continued)  some metal forms more than one cation  use Roman numeral in name  PbCl 2  Pb 2+ is cation  PbCl 2 = lead(II) chloride  some metal forms more than one cation  use Roman numeral in name  PbCl 2  Pb 2+ is cation  PbCl 2 = lead(II) chloride Metals with multiple oxidation states

What to do now? Finish Part 2 of the webquestFinish Part 2 of the webquest Review chapter 1 test materialReview chapter 1 test material