IONIC COMPOUNDS

Review Valence electrons = electrons in outer energy level, participate in chemical bonds Chemical bond = the force that holds two atoms together Forming Ions: positive (cation) = formed by losing electrons, negative (anion) = formed by gaining electrons

Octet Rule & Lewis Dot Diagrams Octet rule : atoms tend to gain, lose, or share electrons in order to acquire a full set (8) valence electrons Lewis Dot Diagrams: valence electrons places as dots around the element symbol

Forming an Ionic Bond Type 1: Binary Ionic compounds = contain only two different elements Ex: NaCl, MgBr2 Type 2: Polyatomic Ionic compounds = contain polyatomic ions, three or more elements Ex: NaOH, NH4Cl, H2SO4 Ions Monatomic Polyatomic Composed of a Single atom Charged group of atoms

Naming Ionic Compounds 1. Name the cation first. It is just the name of the element. 2. Name the anion second. If it is a monatomic anion (only one element) change the ending of the element name to -ide. Example: Chlorine = chloride If it is a polyatomic anion (multiple elements) use the name provided on your blue common ions handout. Example: SO42- = Sulfate

Practice Name the following ionic compounds: NaF KBr AgCl KNO2 Fe(CN)2 MgS2O3

Writing Ionic Formulas Using the Empirical Formula Empirical Formula = ratio of ions in a compound  simplify to lowest whole #’s 1. Determine the charge of each ion. 2. Always write the cation (positive ion) first. 3. Write the anion (negative ion) second. 4. Determine how many of each ion you need to have the charges balance. (criss-cross method) 5. Use parentheses around the ions to separate if necessary. 6. Write the amount of each ion you need as a subscript after the parenthesis.

Practice Write the formulas for the following ionic compounds: Calcium chlorate Potassium iodide Aluminum bromide Aluminum carbonate Sodium sulfate Magnesium phosphate

Al2(CrO4)3 Counting Atoms How do you determine the number of atoms of each element in an ionic compound? Multiply the number of atoms in the ion by the number of ions in the compound. Al2(CrO4)3