Ch 7.1 Forming Ions

Review…  Cations are Groups 1A, 2A, and 3A They have positive charges.  Anions are Groups 5A, 6A, and 7A They have negative charges They end in “ide”  Majority of elements in Groups 4A and 8A do not usually form ions.  These are called monatomic ions!

Ions of Transition Metals  Some transition metals in Groups 1B-8B form more than one cation with different charges.  Examples: Iron forms Fe 2+ and Fe 3+  Two methods of naming: Stock System: Iron (II) ion and Iron (III) ion Classical name: Ferrous ion and Ferric ion *We will use the stock system.

Common Metal Ions with More than One Ionic Charge SymbolStock NameClassical Name Cu + Copper(I) ionCuprous ion Cu 2+ Copper(II) ionCupric ion Fe 2+ Iron(II) ionFerrous ion Fe 3+ Iron(III) ionFerric ion *Hg 2 2+ Mercury(I) ionMercurous ion Hg 2+ Mercury(II) ionMercuric ion Pb 2+ Lead(II) ionPlumbous ion Pb 4+ Lead(IV) ionPlumbic ion

Common Metal Ions with More than One Ionic Charge SymbolStock NameClassical Name Sn 2+ Tin(II) ionStannous ion Sn 4+ Tin(IV) ionStannic ion Cr 2+ Chromium(II) ionChromous ion Cr 3+ Chromium(III) ionChromic ion Mn 2+ Manganese(II) ionManganous ion Mn 3+ Manganese(III) ionManganic ion Co 2+ Cobalt(II) ionCobaltous ion Co 3+ Cobalt(III) ionCobaltic ion

Other Transition Metal Ions  Some transition metals have only one charge and do not use a Roman numeral.  Examples (Write on your periodic table!) Silver: Ag + Cadmium: Cd 2+ Zinc: Zn 2+

Polyatomic Ions  The names of most polyatomic anions end in “-ite” or “-ate”  The “-ite” ending indicates one less oxygen atom than the “-ate” ending  Remember to use parentheses if more than one is needed.

Write the formula that will form between Ba and Cl Solution: 1. Write the positive ion of metal first, and then negative ion Ba 2+ Cl  2. Do the charges equal zero? NO!! 3. Use Criss-Cross method – write subscripts Ba 2+ Cl 1 BaCl 2

Write the correct formula for the compounds containing the following ions: 1. Na +, S Al 3+, Cl - 3. Mg 2+, N Al 3+, S 2-

1. Na +, S 2- Na 2 S 2. Al 3+, Cl - AlCl 3 3. Mg 2+, N 3- Mg 3 N 2 4. Al 3+, S 2- Al 2 S 3

Binary Compound: is composed of two elements and can be either ionic or molecular.

Naming Binary Ionic Compounds  To name a binary ionic compound, place the cation name first, followed by the anion name.  Remember the anion ends in “-ide”  Examples: Cs 2 O NaBr CuO Cesium Oxide Sodium Bromide Copper(II) Oxide

Naming Compounds with Polyatomic Ions  State the cation first and then the anion just as you did in naming binary ionic compounds. KNO 3 Mg(ClO 2 ) 2 Potassium Nitrate Magnesium Chlorite

Naming Binary Molecular Compounds  Binary molecular compound: must be composed of two nonmetals  Use prefixes to indicate the number and kind of atom in the compound  Use the following general format: 1st name: prefix + element name 2nd name: prefix + element name + “ide” If there is only 1 of the 1 st element, no prefix.

Prefixes in Covalent Compounds pg 228 Number of atoms PrefixNumber of atoms Prefix 1mono-6hexa- 2di-7hepta- 3tri-8octa- 4tetra-9nona- 5penta-10deca-

Anyone want a cold glass of dihydrogen monoxide?

Examples  Name the following CO CO 2 N 2 O Cl 2 O 8 Carbon Monoxide Carbon Dioxide Dinitrogen Monoxide Dichlorine Octoxide

Writing Formulas for Binary Molecular Compounds  Use the prefixes in the name to tell you the subscript of each element in the formula.  Then write the correct symbols for the two elements with the appropriate subscripts.  The least electronegative element is written first  Dinitrogen Tetroxide - N 2 O 4

Examples  Write formulas for the following: Nitrogen Monoxide Carbon Tetrachloride Diphosphorous Pentoxide NO CCl 4 P2O5P2O5

Naming Acids  An acid is a compound that contains one or more hydrogen atoms and produces hydrogen ions (H + ) when dissolved in water.  All acids begin with hydrogen  General Format: H n X “X” represents a monatomic or polyatomic anion. “n” represents the number of hydrogen ions

3 Rules for Naming Common Acids  If the name of “X” ends in -ate: ____________-ic acid  If the name of “X” ends in -ite: ____________-ous acid  If the name of “X” ends in -ide: hydro-__________-ic acid

Name these acids  H 2 SO 4  HCl  H 2 S  HNO 3  HClO 2 Sulfuric Acid Hydrochloric Acid Hydrosulfuric Acid Nitric Acid Chlorous Acid

Writing Formulas for Acids  If the acid ends in –ic, then “X” ends in –ate  If the acid ends in –ous, then “X” ends in – ite  If the acid has hydro-______-ic, then “X” ends in –ide.  The subscript on hydrogen is equal to the charge of “X”.

Write the Formula for the Following Acids  Hydrobromic Acid  Carbonic Acid  Phosphoric Acid  Sulfurous Acid HBr H 2 CO 3 H 3 PO 4 H 2 SO 3

Homework  7.1 pg 251 #14, 15(no g), 41