Ionic Charges Group 1A +1 Group 2A +2 Group 3A +3 Monatomic ions formed as follows: Group 1A +1 Group 2A +2 Group 3A +3 Al is only common Group 3A metal

Groups 1A- 3A form cations- Ionic charge is positive and equal to the group number Group A nonmetals form anions- ionic charge is negative and equal to 8 – group number

Group A Nonmetals Group 7A -1 Group 6A -2 Group 5A -3 Group 4A and O usually do NOT form ions

Group O rarely form compounds Nonmetals in Group 4A - C and Si form molecular compounds

Transition Metals Have more than one ionic charge Also true of metals in Group 4A- Pb and Sn

Naming Transition Ions Stock System- name of element (roman numeral-charge) Sn+4 Tin (IV) ion

Naming Transition Ions Classical System- -ous for lower ionic charge -ic for higher ionic charge Sn+4 Stannic ion

Classical Name Related to Symbol Fe - ferrous / ic Pb - plumbous / ic Sn - stannous / ic Disadvantage- do not know the charge of the ion

Transition Metals with only one ionic charge Ag + Cd +2 Zn +2

Practice Write the symbol & charge for the ion of each atom: Barium Selenium Chromium 3 e- lost Neon Iodine Iron 2 e- lost Ba+2 Se-2 Cr+3 No ion formed I – Fe +2

Polyatomic Ions Composed of more than one atom Tightly bonded and function as a unit and carry a charge Nitrate NO3- 1 Nitrogen and 3 Oxygen Most end in –ate or -ite

Exceptions NH4+ ammonium CN- cyanide OH- hydroxide

-ite/ -ate pairs So3-2 sulfite SO4-2 sulfate NO2- nitrite NO3- nitrate ClO2- chlorite ClO3- chlorate -ite ending has 1 less Oxygen than -ate (charges are same)

Polyatomic H ions Begins with H Think of it as H+ + another polyatomic Hydrogen carbonate H+ + CO3-2 HCO3- Sum of charges

Hydrogen phosphate H+ + PO4-3 HPO4-2 Dihydrogen phosphate H+ + HPO4-2 H2PO4-

HCO3- , HPO4-2 , H2PO4- Essential for life CN- (Cyanide) poison- blocks energy production ClO- (Hypochlorite) bleach

Naming Ionic Compounds Section 9.2

Antoine-Laurent Lavoisier French Chemist Developed systematic method for naming chemical compounds

Binary Ionic Compounds Place Cation name first, followed by Anion name Cs2O Cesium oxide SrF2 Strontium fluoride

Additional Naming CuO Not Copper oxide Cu+ or Cu2+ Therefore: Copper (II) oxide or Cupric oxide Try SnF2 and SnS2

SnS2 SnF2 Sn2+ or Sn4+ Ratio 1:2 F-1 So Sn2+ Sn2+ or Sn4+ Ratio 1:2 Tin (II) fluoride or Stannous fluoride Sn2+ or Sn4+ Ratio 1:2 S-2 So Sn+4 Tin (IV) sulfide or Stannic sulfide

Writing Formulas Write the symbol of the cation and then the anion. Add subscripts needed to balance the charges.

Fe+3 + O-2 Crisscross charges Fe2O3 Iron (III) oxide Fe+3 + O-2 Crisscross charges Fe2O3

Ca+2 + S-2 Ca2S2 But want lowest whole number ratio, so: CaS Calcium sulfide Ca+2 + S-2 Ca2S2 But want lowest whole number ratio, so: CaS

Compounds with Polyatomic Ions Write the symbol for the cation followed by the formula for the polyatomic ion, and then balance the charges. Calcium nitrate Ca+2 + (NO3)-1 Crisscross charges for subscripts Ca1(NO3)2 so: Ca(NO3)2