Names and Formulas of Ionic Compounds 3.2 Names and Formulas of Ionic Compounds

Objectives By the end of the lesson you should be able to: Describe simple and complex ions Name and write formulas for all types of ionic compounds

WARM UP! Counting Atoms Practice Formula # of Atoms NaCl Mg(OH)2 HNO3 (NH4)2O H2SO4 NH4NO3 2 5 5 11 7 9

Complex and Simple Ions Simple Ions: one atom with a charge H+ S-2 Cu+1 Cu+2 Complex Ions: more than one atom with an overall charge Called polyatomic ions Listed on pg 92 in your textbook SO4-2 NO3-1 NH4+1

Remember… ALL ELEMENTS WANT TO HAVE FULL OUTER SHELLS! The combining capacity (AKA: ion charge) tells you how many electrons have been lost/gained to get a full outer shell

Names and Formulas Naming compounds: involves writing out the entire name for each element in the compound Compound and symbols given  make name! Formulas: involve using symbols of each element to make the compound Name given  make compound with symbols

Ionic Compounds Always involve a positive charge (metal) and a negative charge (non-metal) Electrons are always transferred from the positive to the negative Create ions because losing and gaining electrons (charges result)

Rules for Naming Ionic Compounds Metal always first; name never changes Non-metal second; ending becomes “ide” EX: NaCl = sodium chloride MgF2 = magnesium fluoride Al2O3 = aluminum oxide

Your Turn! Practice Problems pg. 86 (check your answers on page 509!)

Chemical Formulas of Ionic Compounds Formulas contain symbols to identify each ion in an ionic compound, as well as the relative numbers of ions in the compound. Example: NaCl – 1 sodium:1chlorine CaF2 – 1 calcium:2 fluorine atoms Note: Relative numbers of each ion is a subscript to the right of the symbol

Ionic Compound Formulas Get symbol and charge Charges are the same skip to step 2 If charges are different “swap and drop” Combine

Ionic Compound Formulas Calcium chloride (write the symbols) Ca Cl (superscript combining capacities) Ca 2+ Cl 1- Ca 2+ Cl 1-(drop the +/- signs and cross combining capacities) 5. CaCl2

Your Turn! Practice Problems pg. 87 (check your answers on page 509!)

Multivalent Ionic Compounds Multivalent = more than one possible combining capacity (ion charge) Found in the Transition Metals section Same naming as Ionic Compounds BUT use a roman numeral to show which combining capacity is used I II III IV V VI VII VIII 1 2 3 4 5 6 7 8

Multivalent Ionic Compound Formulas (Roman Numeral given) Get symbol and possible charges Choose appropriate ion (from Roman Numeral) Charges are the same skip to step 2 If charges are different “swap and drop” Combine Reduce to lowest common ratio if need Ex. Iron (III) oxide = Iron (II) oxide = Lead (IV) oxide = Fe2O3 FeO PbO2

Your Turn! Practice Problems pg. 89 (every 2nd question: a, c, e, g, i, k, m, o) (check your answers on page 509!)

Compounds Containing Multivalent Metals Notice that some metallic elements have more than one possible ion charge. We need to use Roman Numerals to indicate which combining capacity is used. E.g. Copper (II) chloride  Cu +2 E.g. Copper (I) chloride  Cu +1

Naming Multivalent Ionic Compounds (no Roman Numeral given) Get possible charges Determine which charge will give the correct formula (reverse swap and drop) Write the name same as you did with Ionic Compounds Add the appropriate Roman Numeral between the metal and non-metal

Naming: Multivalent Metal Use the Roman Numeral equal to the ionic charge to indicate which combining capacity was used E.g. CuCl2 Cu1+ or Cu2+ ? Copper (II) chloride E.g. Fe2O3 Fe3+ or Fe2+ ? Iron (III) oxide You need to reverse swap and drop to find combining capacities (ion charges).

Your Turn! Practice Problems pg. 90 (every 2nd question: a, c, e, g, i, k, m, o) Check answers on page 509!

Naming Polyatomic Ionic Compounds Usually seen in more complicated compounds List of Polyatomic Ions is found in your textbook on pg.92 and on the back of your periodic table during tests! Look up both names Check for multivalent charges and insert Roman Numerals if need be Combine Ex. NH4OH FeCrO4 Ammonium hydroxide Iron (II) chromate

Polyatomic Ionic Compound Formulas Get symbol and possible charges If same skip to step 2 If different “swap and drop” Combine – use brackets if need be for polyatomic ions ONLY

Polyatomic Ionic Compound Formulas E.g. Ammonium sulfide Ammonium = NH4 1+ (1+ is the ion charge) (given on the back of the Periodic Table) When NH4 1+ and S-2 combine, the NH4 polyatomic ion group stays together You need to put brackets around NH4 so you can separate the digits then swap and drop. So, (NH4) 1+ S 2- (NH4)2 S

Polyatomic Ionic Compound Formulas Ex. Ammonium hydroxide = Ammonium carbonate = NH4OH (NH4)2CO3

Your Turn! Practice Problems pg. 91 (every 2nd question: a, c, e, g, i) Check answers on page 509! Worktime! Workbook p. 47 – 49 Textbook p. 95 for extra practice if you need! Names & Formulas quiz next day!